Research On Resource Allocation Strategy Of Large Scale Machine Type Communication

Machine-type communication(MTC)is an important part of the Internet of Things.It can be applied to intelligent transportation,smart cities,smart meters and industrial control,and has a wide market prospect.However,at the same time,because the characteristics of the MTC service are very different from those of the traditional cellular network,and MTC also has the characteristics of large number of devices,low power consumption,and uplink domain,which will bring great challenges to the existing cellular network.In order to improve the the number of connected MTC devices(MTCD)and reduce the power consumption of MTCD,this thesis has carried out the following research on resource allocation strategies for large-scale machine-type communication:Firstly,we consider the problem of maximizing the number of connected MTCDs,and a resource allocation scheme for joint subcarrier and power under power-domain non-orthogonal multiple access(NOMA)is proposed.In this thesis,we analyze the situation where multiple MTCDs use the same subcarrier together,and a nonlinear integer programming problem that maximizes the number of connected MTCDs is formulated.Due to the fact that this problem is non-convex and discontinuous,the problem is broken down into two sub-problems:the first sub-problem is the combination of ultra-reliable Machine Type Communication devices(uMTC)selected for each subcarrier,and the second sub-problem is the combination of massive Machine Type Communication devices(mMTC)selected for each subcarrier.Then,the original problem is solved by solving the sub-problems separately.The simulation results show that compared with the existing NOMA schemes,the proposed scheme can effectively improve the number of connected MTCDs.Secondly,we study the resource allocation problem of gateway-assisted MTCDs upload data under power domain NOMA.And a machine-type communication gateway(MTCG)selection scheme based on the lowest energy consumption is proposed.The scheme considers the communication resource allocation problem when the MTCGs assist the MTCDs to upload data to the base station,and considers the communication resource allocation problem when the MTCDs directly upload data to the base station.Then we comprehensively consider these two situations,and develop the MTCG selection problem with the lowest MTCD total energy consumption.The MTCG selection scheme based on the lowest energy consumption in the power domain NOMA is proposed to solve this problem.The simulation results show that compared with the existing TDMA schemes,the proposed scheme can effectively reduce the total energy consumption of MTCDs.Thirdly,we study the problem of maximizing the number of MTCD-MTCD device pairs in the same frequency band as the MTC cluster multiplexing,and a new resource allocation scheme is proposed.In this thesis,we analyze the judgment conditions of whether MTCD-MTCD device pairs can use the same time-frequency resources with MTC cluster.Then we develop a nonlinear integer programming problem aiming at maximizing the number of MTCD-MTCD devices.And in order to solve this problem,a scheme based on greedy algorithm is proposed to maximize the number of MTCD-MTCD device pairs.The simulation results show that compared with the existing resource allocation scheme based on graph coloring algorithm under fixed transmit power,the proposed scheme can effectively improve the number of MTCD-MTCD device pairs when reusing the same time-fr-equency resources with the MTC cluster.