Study On Joint Resource Allocation In CoMP Joint Transmission-based Heterogeneous Networks

By deploying low power transmission nodes within the coverage of the traditional macro cells,the shortened distance between base stations and user equipments in heterogeneous networks(Het Nets)can significantly enhance the signal strength and then improve the system capacity.Het Nets has been regarded as an important network infrastructure for 5G.However,since the cells at different tiers usually share the same spectrum to achieve a high spectral efficiency,cross-tier cochannel interference is a critical issue for Het Nets preventing the further performance improvements.At present,deploying coordinated multipoint(Co MP)technique into Het Nets may mitigate or even eliminate the cross-tier interference by cooperatively scheduling the resources of base stations.It is a new research topic in the domain of heterogeneous networks.This paper focuses on the joint channel and power allocation in Het Nets with Co MP joint transmission support.Resource allocation schemes for achieving high spectral efficiency and fairness are designed respectively.We deeply studied various methods,including large problem decomposition and iteration,to reduce the complexity of the joint allocation of channel and power resources and design reasonable and effective resource allocation algorithms.The main contributions obtained in this paper are as follows:(1)A joint channel and power allocation scheme is proposed for Het Nets under Co MP joint transmission mode to achieve high spectral efficiency.The scheme is formulated as maximizing the overall throughput of the system,and then an iterative joint resource allocation algorithm with relatively low complexity is designed.The original problem is decomposed into the channel allocation subproblem and the power allocation subproblem,and then solved iteratively until convergence.The simulation results show that the proposed scheme can obtain higher system throughput than the existing resource allocation schemes,and the algorithms converge within few iterations.(2)The joint allocation channel and power allocation scheme with the consideration of both system spectrum efficiency and user fairness is further studied.Aiming at maximizing the worst user throughput,a mathematical model is established,and then an iterative algorithm based on Lagrange dual decomposition is designed.The original problem is decomposed into 4 subproblems,and the channel allocation algorithm and the power allocation algorithm based on iteration and bisection methods are designed respectively.Finally,the performance of the proposed scheme in terms of user throughput and fairness,and the fast convergence of the algorithm are verified by simulation.