SCMA系统中层分配及功率分配方案研究

发布时间：2018-04-02 00:23

本文选题：5G　切入点：稀疏码多址接入(Sparse　出处：《西南交通大学》2016年硕士论文

【摘要】：随着通信技术的不断发展和用户业务需求的日益增长,第五代(The 5th Generation, 5G)移动通信系统的研究开始受到学术界的高度关注,根据业界提出的5G系统的核心性能指标和系统设计需求,5G网络希望支持更高的吞吐量、更低的时延、更好的服务质量(Quality of-Service, QoS)以及海量链接等。由于4G正交多址技术中接入的用户数和正交资源成正比,因而不能满足未来大容量、海量连接、超低延时接入等的需求,进而非正交多址接入技术就成为当下5G多址接入的研究重点。本文主要针对华为公司提出的当下主研的非正交技术之一,稀疏码多址接入(Sparse Code Multiple Access, SCMA)技术,研究分析SCMA主要关键技术,包括SCMA过载性能分析,在面向过载的SCMA传输系统中,分别设计基于容量的SCMA层资源及功率分配方案和基于能效的SCMA层资源及功率分配方案,仿真分析其性能。主要的研究内容如下：第一,首先介绍了SCMA技术的基本原理,然后详细分析了SCMA上行链路设计、SCMA下行链路设计、SCMA接收机检测方案以及SCMA技术的优势,为后续性能分析及方案设计奠定了基础。第二,主要针对SCMA的过载特性,分别仿真分析了SCMA过载因子与码本的关系和过载因子对系统误码性能的影响,并比较了SCMA与LDS (Low Density Signature)的码字稀疏性能在相同过载程度下,SCMA误码性能优于LDS。最后分析过载因子与系统容量之间的关系,分析了用户数目、码本个数、层功率等对系统容量的影响。第三,在面向过载的SCMA传输系统中,针对提升系统容量和系统能效,分别提出了最大化系统容量和系统能效的SCMA层分配及功率分配方案,并利用拉格朗日对偶理论求解了SCMA层分配矢量及其上的最优功率,最后通过仿真验证了所提方案的有效性。仿真结果表明,与平均功率算法相比,在基于最大化系统容量的层分配及功率分配算法下系统容量有显著提高,在基于最大化系统能效的层分配及功率分配算法下系统能效也有显著提高。
[Abstract]:With the continuous development of communication technology and the increasing demand of user service, the research of the fifth generation of the 5th Generation (5G) mobile communication system has been highly concerned by the academic community.According to the core performance index of 5G system and the system design requirement, 5G network hopes to support higher throughput, lower delay, better quality of service (QoS) and mass links.Because the number of users in 4G orthogonal multiple access technology is proportional to the orthogonal resources, it can not meet the needs of large capacity, mass connection, ultra-low delay access and so on in the future.Furthermore, non-orthogonal multiple access technology has become the focus of 5 G multiple access research.Aiming at one of the current non-orthogonal technologies proposed by Huawei, sparse Code multiple access (Sparse Code Multiple access) technology, this paper studies and analyzes the main key technologies of SCMA, including SCMA overload performance analysis, in overload-oriented SCMA transmission systems.The capacity based SCMA layer resource and power allocation scheme and the energy efficiency based SCMA layer resource and power allocation scheme are designed, and their performance is analyzed by simulation.The main research contents are as follows: firstly, the basic principle of SCMA technology is introduced, and then the SCMA uplink design and the downlink design of SCMA receiver are analyzed in detail, as well as the advantages of SCMA technology.It lays a foundation for subsequent performance analysis and scheme design.Secondly, aiming at the overload characteristics of SCMA, the relationship between SCMA overload factor and codebook and the influence of overload factor on system error performance are simulated and analyzed respectively.The code-sparsity performance of SCMA and LDS low Density signature is compared with that of LDSs in the same degree of overload.Finally, the relationship between the overload factor and the system capacity is analyzed, and the influence of the number of users, the number of codebooks and the layer power on the system capacity is analyzed.Thirdly, in the overload oriented SCMA transmission system, in order to improve system capacity and system energy efficiency, a scheme of SCMA layer allocation and power allocation is proposed to maximize system capacity and system energy efficiency, respectively.The SCMA layer distribution vector and its optimal power are solved by using Lagrange duality theory. Finally, the effectiveness of the proposed scheme is verified by simulation.The simulation results show that compared with the average power algorithm, the system capacity is significantly improved under the layer allocation and power allocation algorithm based on maximizing system capacity.The system energy efficiency is also significantly improved under the hierarchical allocation and power allocation algorithm based on maximizing system energy efficiency.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN929.5

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