Research On Fairness Resource Allocation Of D2D Communication System Based On Convex Optimization Theory

With the rapid development of mobile Internet,the spectrum resources of traditional cellular wireless communication systems is not enough to meet the needs of current communication.Device-to-Device(D2D)communication technology has a flexible and efficient resource reuse schemes,and users can directly reuse spectrum resources of cellular users to improve spectrum utilization,which has drawn considerable attentions among researchers.Due to the difference of communication channel status,users with poor channel status are difficult to get communication opportunities,and even the phenomenon of "starvation" will appear.How to make users obtain fair communication opportunities in the process of communication is the focal point of resource allocation research.In addition,due to the large amount of data transmission and the increase of energy consumption of the equipment itself,the acquisition of energy for wireless communication equipment has been put forward higher requirements,and energy collection technology as a key technology to enhance and improve the endurance of the equipment has attracted much attention.Therefore,for the D2D wireless communication system without energy collection device and with energy collection device,in order to meet the user's demand for fairness of communication system,this paper studies the fair resource allocation strategy.On the basis of problem planning,the convex optimization theory is used to solve the problem,and simulation analysis is carried out.The main work of this thesis includes:(1)In order to improve the fairness between D2D users effectively and take the QoS of communication into account,the resource allocation problem of D2D communication system is studied by using a-fair utility function.Under the premise of guaranteeing the QoS of cellular system communication,aiming at maximizing the total utility of D2D users,the joint optimal allocation of power and resource blocks in the communication system is carried out.Then,the optimization problem is established and the fairness allocation strategy of joint optimization is put forward.In the process of solving,the non-convex optimization problem is transformed into a convex problem.and the optimization problem is divided into the main problem and the sub-problem by using the dual decomposition theory.Finally,the expression of the optimal solution is obtained by using the Lagrangian dual method.On the basis of the above work,the gradient descent method and one-dimensional search method are used to calculate the sub-problem and the main problem respectively.Then,the numerical simulation is carried out after solving the problem.The simulation results show that the joint optimal fairness allocation strategy proposed in this thesis can make the allocation of communication resources more fair and can better balance the total rate of D2D users and the rate of each user.(2)In order to bet.ter satisfy user's demand for continuous energy supply and quality of service,the fairness resource allocation strategy of D2D communication system based on energy collection is studied in this paper.Under the premise of guaranteeing the QoS and energy collection causality of cellular system communication,the optimization problem is established to maximize the total utility of D2D users.After transforming the non-convex mixed integer nonlinear programming problem into a convex problem.the optimal solution expressions of transmission power and resource allocation factor are derived by using Lagrangian duality method.On this basis,numerical calculation and simulation are carried out to study the impact of maximum energy storage value on resource allocation,average rate allocation of D2D users in each slot,convergence of algorithm and comparison with other optimization strategies.The simulation results show that the proposed strategy can achieve fair resource allocation,and compared with the fixed resource block strategy and fixed power allocation strategy.it can achieve higher system throughput.