Research On Non-orthogonal Multiple Access In MIMO System

Non-orthogonal multiple access(NOMA)in power domain is a non-orthogonal multiple access technology for sisgnal superposition in the power domain.It is also a promising candidate for 5G multiple access technolog}y.NOMA can increase system throughput and increase spectrum efficiency without increasing system bandwidth.The combination of NOMA and MIMO can further increase system capacity.In addition,the current communication sy'stem can only support the data service of low-speed mobile users,and the performance of the cellular system is greatly degraded in the high-speed mobile scene.Therefore,it is necessary to study the communication problem in the high-speed mobile scene by virtue of the advantages of the MIMO-NOMA system.In addition,the user clustering algorithm of the MIMO-NOMA system play's a key role in the rate increase of weak users,which can reduce the inter-cluster interference and fur-ther improve the performance of the NOMA.In this paper,the NOMA technology in MIMO system serves the local users and high-speed rail users simultaneously,the NOMA user SNR approximation and the NOMA user clustering algorithm optimization are studied.The MIMO system is proposed to serve both high-speed rail users and local users.The NOMA system model deduces the single-user SNR approximation formula,designs the NOMA system-level simulation platform,provides simulation data,and simulates the proposed system theory and peirformance.In addition,the user clustering algorithm of NOMA is improved to better suppress the inter-cluster interference,and the simulation results show that the proposed algorithm can improve the system performance.Firstly,it introduces the principle,key technology,system model and comparison with OMA of NOMA.Then it introduces the model and key technologies of MIMO system,including precoding,and two schemes combining NOMA and multi-antenna.This paper focuses on the system model and system interference processing and performance analysis of MIMO-NOMA combined to provide services for high-speed rail users and local users.Secondly,the single-user SNR approximation scheme of MIMO-NOMA system is introduced.The system-level simulation is established.The simulation results verify the performance advantages of the proposed system scheme compared with traditional MIMO-NOMA and MIMO-OMA.Finally,the performance of MIMO-NOMA is optimized by the improvement of Luser clustering algorithm.This paper introduces the traditional user clustering algorithm principle,compares the advantages and disadvantages of traditional algorithms,focuses on the improved K-means-based user clustering algorithm and realizes the performance optimization of MIMO-NOMA through simulation verification.