Research On Resource Allocation In OTFS-MIMO-NOMA Systems

High speed mobility will be an important scenario for the future 6G mobile communication(6th Generation).In space-air-ground networks such as satellite Internet,UAV network and Internet of vehicles,Doppler shift caused by high mobility has aroused widespread concern in academia and industry.To solve the above problems,this thesis introduces OTFS(Orthogonal Time Frequency Space)technology,and designs the user-DD(Delay Doppler)grid matching scheme and power allocation scheme under the premise of ideal pulse waveform,integer Doppler resolution,non ideal pulse waveform and fractional Doppler resolution respectively for single antenna and multi-antenna deployment scenarios.The specific research contents are as follows.First,for the single antenna deployment scenario,this thesis designs a resource allocation scheme in OTFS-NOMA(Non Orthogonal Multiple Access)system on the premise of adopting ideal pulse waveform and integer Doppler resolution.Firstly,according to the characteristics of downlink communication in high-mobility networks,the resource allocation problem is modeled as a system sum rate maximization problem,and the multivariable coupling nonlinear problem is further decoupled into two independent subproblems.Secondly,user-DD grid matching schemes are designed based on KM(Kuhn Munkras)algorithm,GS(Gale Shapley)algorithm and NIMP(National Inter Matching Program)algorithm.Then,an iterative power allocation scheme based on fractional order algorithm and successive convex approximation is designed.Finally,an iterative communication resource allocation scheme is designed by combining userDD grid matching and power allocation.Simulation results verify that the proposed NIMP matching scheme has a good improvement in complexity and system sum rate.Compared with other algorithms,the iterative power allocation scheme and joint allocation scheme have a significant improvement in sum rate performance.Secondly,in order to make full use of spatial diversity,this thesis studies the communication resource allocation scheme in OTFSMIMO(Multiple Input Multiple Output)-NOMA system for multi-antenna deployment scenarios.Firstly,for the downlink of high-mobility communication network with non ideal pulse waveform and fractional Doppler resolution,the signal demodulation recovery is realized through signal processing such as precoding at the transmitter and low complexity signal detection at the receiver;Secondly,considering the key characteristics of OTFS,MIMO and NOMA systems,the resource allocation problem is modeled as a system sum rate maximization problem.Then,a new preference sequence between user and grid is proposed,and a user-DD grid matching scheme with strict preference is designed based on GS algorithm.Finally,based on genetic algorithm,the power allocation schemes of users in different grids are designed.Simulation results verify that the proposed strict preference matching scheme based on GS and the power allocation scheme based on genetic algorithm have obvious sum rate performance improvement compared with other algorithms.