Resource Allocation Based On Non Orthogonal Multiple Access And Full Duplex Communication In Two-tier Heterogeneous Networks

In recent years,with the exponential growth of smart phones and mobile services,the traditional cellular network has been unable to meet the demand.In order to improve the utilization rate of spectrum resources and the energy efficiency of the system,and meet the requirements of user service quality,the academic and industrial circles put forward the framework of two-tier heterogeneous cellular network from the perspective of network architecture,that is,to introduce small base stations with low transmission power into the traditional macrocell to overlap the hot areas.With the development of heterogeneous cellular network,how to further improve the system capability becomes a new problem in the research of heterogeneous cellular networks.Considering the advantages of full duplex communication technology in improving spectrum efficiency,full duplex communication technology is introduced into heterogeneous cellular network,so that wireless devices can transmit and receive data in the same frequency band at the same time.In addition,with the development of the fifth generation mobile communication(5G)and the improvement of hardware capabilities,it is possible to use non orthogonal multiple access(NOMA)technology to further improve the spectral efficiency of the system.In this paper,the optimal allocation of wireless communication resources is studied in the case of uncertain channel gain information for a two-tier heterogeneous network based on NOMA technology and full duplex communication technology.Firstly,considering the uncertainty of channel,we propose a scheme of joint power control for the macro base station and the small base station in two-tier NOMA heterogeneous networks.Considering the different service requirements of macro base station users and small base station users,and in order to effectively suppress cross layer interference and realize low power transmission,a hierarchical power control game framework is proposed.The simulation results show that the power control algorithm based on hierarchical game can effectively guarantee the quality of service of users,and has good robust performance.Secondly,this paper proposes a method to solve the problem of user associationand power control in the two-tier NOMA heterogeneous networks.The form of probability constraint is used to describe the channel uncertainty in the real communication environment.In order to maximize the total energy efficiency of the system and reduce the intra-cell and inter-cell interference,the joint optimization problem is established in the NOMA network with uncertain channel gain.A simple distributed user association algorithm is proposed to determine the user association.By using integral transformation and successive convex approximation(SCA),the problem is transformed and the power control algorithm is given.Simulation results show that the joint allocation algorithm has good robustness and effectiveness in dynamic communication environment.Finally,the power control problem of full duplex communication in the two-tier femtocell network is studied,where femtocells share the same frequency with macrocell uplink.Considering the channel uncertainty in the real communication environment and the cross-tier and co-tier interference among users,aiming at improving the quality of service and reducing the power consumption,a hierarchical power allocation game framework is proposed to maximize the utility of uplink and downlink users.According to different design objectives,the uplink guarantees marginal utility and the symbol error rate(SER),and the downlink guarantees transmission rate and delay.The Lagrangian method and sub-gradient method are used to solve the optimization problem,and the power iteration algorithm for game equilibrium is given.Simulation results show that the algorithm has good performance in convergence,robustness and quality of service.