Design And Optimization Of Cell Range Expansion Strategies Based On Interference Coordination

In recent years,due to the increase of mobile devices,data traffic growth and user access have also increased dramatically,which has caused serious traffic congestion in the network.In order to solve the problem of massive traffic growth in 5G networks in the future,researchers propose to deploy small base stations within the coverage of macro base stations,and use the cell range expansion strategy(CRE)to achieve load balancing between macro base stations and small base stations.However,users in the CRE area will receive the co-channel interference from the macro base station,resulting in a decrease in network performance.Improving the network energy efficiency through the interference coordination strategy has become a very important research hotspot in today's network research.Based on the full understanding of the research on cell range expansion strategy in heterogeneous networks at home and abroad,this paper deeply studies the energy efficiency optimization problem of cell range expansion strategy based on different interference coordination techniques,and jointly optimizes cell range expansion bias under different interference coordination strategies.The extended bias value and the interference control variable are optimized for energy efficiency,and finally a better energy efficiency optimization system is developed.The main research work of this paper is as follows:(1)The energy efficiency optimization of the cell range expansion strategy based on almost blank subframe(ABS)is proposed.For the cell range expansion area users,the problem of severe co-channel interference of the macro base station is introduced.ABS strategy is introduced,and an iterative optimization algorithm that jointly optimizes the CRE bias value and the ABS ratio is proposed.For the problem of CRE bias value and ABS ratio constraint,the CRE bias value and ABS ratio are searched to find the optimal solution,and then iterative joint optimization algorithm is used to update the iteration to maximize the system energy efficiency.Finally,the proposed iterative joint optimization algorithm is verified by MATLAB simulation.(2)The energy efficiency optimization of the cell range expansion strategy based on low power almost blank subframe(LP-ABS)is proposed.The LP-ABS-based system model is based on 1),but the difference is that during ABS,the macro base station no longer only transmits basic information,but reduces power to service macro base station users,so on the basis of 1),It also increases the interference of the macro base station that reduces power operation to the extended user.For the system adopting LP-ABS strategy,after establishing the LP-ABS-based model,the CRE bias value and the macro base station power ratio are jointly optimized,and the optimal system energy efficiency is obtained by the alternating optimization algorithm.Finally,the scheme is verified by MATLAB.(3)The energy efficiency optimization of the cell range expansion strategy based on power control is proposed.For the macro-pico scenario,consider the same layer interference and cross-layer interference.A heuristic algorithm that jointly optimizes the power control factor and CRE bias value and maximizes the network energy efficiency is proposed.Firstly,the power control strategy is introduced for the heterogeneous network adopting CRE strategy,and the system energy efficiency expression is obtained through system modeling analysis.For the problem of power control factor and CRE bias value constraint,it is divided into two steps to optimize and obtain the optimal solution.Then it is jointly optimized by heuristic energy efficiency optimization algorithm to maximize the system energy efficiency,and then apply MATLAB for simulation.