Research On Resource Allocation With Energy Efficiency In Heterogeneous Networks

Wireless cellular networks have developed rapidly with the introduction of smartphones,tablets and other new mobile devices.More data-intensive services and mobile data traffic have increased dramatically.In the case,low-power small base stations are deployed in the same geographical area of the macro cell network to form heterogeneous networks(Het Nets).Het Nets can greatly improve the system capacity and coverage,and effectively improve the energy efficiency of the system.Although heterogeneous architecture brings rich network topologies,the deployment of different low-power base stations and the uncertainty of user deployment will cause severe challenges in the user association and interference management of energy efficiency.Low power consumption and high energy efficiency have gradually been introduced into wireless communication systems.Therefore,the industry uses effective resource management methods to improve system energy efficiency in Het Nets.User association,sub-channel allocation and power control are important contents of resource management,which can balance the service load between base stations and reduce mutual interference between cells and energy consumption of base station equipment.The main contents of this dissertation are specifically arranged as follows:First,the fundamental theories of resource management in Het Nets are outlined,including Het Nets architecture,non-orthogonal multiple access(NOMA)technology,energy efficiency measurement standards and resource management methods.Second,we construct a system model of two-layer Het Nets and consider no co-frequency interference between small cells.After that,a joint user association and small cell user power allocation scheme is proposed to solve the problem of maximizing energy efficiency under the condition of meeting the user's quality of service requirements and the maximum power constraint.In the scheme,we map the user association variable to the position of the artificial fish using the artificial fish swarm algorithm(AFSA),convert the system energy efficiency into the food concentration of the artificial fish at a specific location,and performs iterative optimization to determine the best user association.Moreover,the alternating direction method of multipliers(ADMM)is used to solve the problem of small cell user power allocation.Numerical simulation results show that the proposed scheme converges faster and can significantly improve energy efficiency compared with the existing schemes.Third,a joint subchannel and power allocation scheme is proposed to improve the energy efficiency of small cells with energy harvesting(EH)unit in NOMA Het Nets,where the constraints of maximum transmission power,SINR threshold,and cross-layer/co-layer interference are considered.In this scheme,a modified Gale-Shapley algorithm with interference hypergraph is designed for subchannel allocation.Note that the algorithm can dynamically adjust the number of small cells on the same subchannel.Moreover,the Lagrangian dual method is utilized to optimize power allocation of small cell users.Numerical simulation results are presented to demonstrate that the proposed scheme achieves superior performance compared with existing well-known methods.