SCMA系统在下行链路中的截止速率研究
发布时间：2019-03-11 08:05
【摘要】：稀疏码分多址(Sparse Code Multiple Access,SCMA)是一种专门针对第五代移动通信系统(5G)提出的,非正交的,多址技术,该技术以低密度扩频(Low Density Signature,LDS)多址技术为基础,通过引入多维复数码本/星座图(Codebook/Constellation)的概念进一步获得了额外的系统编码与赋形增益。作为前景广阔的非正交多址(Non-Orthogonal Multiple Access,NOMA)技术之一,SCMA系统能够实现非常高的频谱利用率。它不仅可以满足未来5G通信网络对海量用户连接的需求,同时还能够体现出高可靠、短时延、低功耗等多种优点。本论文介绍了 SCMA系统的基本模型及其相关技术,对比于LDS-CDMA系统,详细介绍了 SCMA收发端原理和性能改进,并针对接收端检测的消息传递算法(Message Passing Algorithm,MPA)的基本思想和运行原理进行了具体的讲解。本文给出了几种常见的SCMA码本设计思想,主要应用于SCMA码本母星座的设计。并通过对比SCMA的物理层模型,给出了 SCMA上/下行链路的相似性和差异性。SCMA系统容量的分析一直是相关课题的难度问题之一。我们通过分析其截止速率在一定程度上解决了相关问题。截止速率可以看作系统容量的下限,可用于表征系统可靠性,也可以用来判断不同SCMA码本的系统性能优劣。本论文介绍了典型系统的截止速率及其重要相关参数,并进一步将其应用于SCMA系统的分析。为了增加SCMA系统截止速率分析的准确性,本论文给出了一种基于云状分割(CloudPartition,CP)思想的分析方法,适用于SCMA下行链路。在此基础上,对SCMA下行链路基于AWGN和Rayleigh两种信道下的截止速率进行了理论分析。通过仿真结果,验证了相关理论推导的实用性和准确性。
[Abstract]:Sparse Code Division multiple access (Sparse Code Multiple Access,SCMA) is a non-orthogonal, multi-access technology specifically designed for the fifth generation mobile communication system (5G), which is based on low density spread spectrum (Low Density Signature,LDS (LDSS) multiple access technology. By introducing the concept of multi-dimensional complex digital book / constellation graph (Codebook/Constellation), the additional system coding and shaping gain are obtained. As one of the promising non-orthogonal multiple access (Non-Orthogonal Multiple Access,NOMA) technologies, SCMA system can achieve very high spectrum efficiency. It can not only meet the needs of the future 5G communication network for massive user connections, but also show many advantages such as high reliability, short delay, low power consumption and so on. In this paper, the basic model of SCMA system and its related technologies are introduced. Compared with LDS-CDMA system, the principle and performance improvement of SCMA transceiver are introduced in detail, and the message passing algorithm (Message Passing Algorithm, for receiver detection is also introduced in detail. The basic idea and operation principle of MPA are explained in detail. In this paper, several common SCMA codebook design ideas are presented, which are mainly used in the design of SCMA codebook mother constellation. By comparing the physical layer model of SCMA, the similarity and difference of SCMA uplink / downlink are given. The analysis of SCMA system capacity has always been one of the difficult issues. We have solved the related problems to some extent by analyzing its cut-off rate. The cut-off rate can be regarded as the lower limit of the system capacity, can be used to characterize the system reliability, and can be used to judge the system performance of different SCMA codebooks. This paper introduces the cut-off rate of the typical system and its important parameters, and further applies it to the analysis of the SCMA system. In order to improve the accuracy of cut-off rate analysis for SCMA systems, this paper presents an analysis method based on cloud segmentation (CloudPartition,CP), which is suitable for SCMA downlink. On this basis, the cut-off rate of SCMA downlink based on AWGN and Rayleigh is analyzed theoretically. Through the simulation results, the practicability and accuracy of the relevant theoretical derivation are verified.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5
本文编号：2438107
[Abstract]:Sparse Code Division multiple access (Sparse Code Multiple Access,SCMA) is a non-orthogonal, multi-access technology specifically designed for the fifth generation mobile communication system (5G), which is based on low density spread spectrum (Low Density Signature,LDS (LDSS) multiple access technology. By introducing the concept of multi-dimensional complex digital book / constellation graph (Codebook/Constellation), the additional system coding and shaping gain are obtained. As one of the promising non-orthogonal multiple access (Non-Orthogonal Multiple Access,NOMA) technologies, SCMA system can achieve very high spectrum efficiency. It can not only meet the needs of the future 5G communication network for massive user connections, but also show many advantages such as high reliability, short delay, low power consumption and so on. In this paper, the basic model of SCMA system and its related technologies are introduced. Compared with LDS-CDMA system, the principle and performance improvement of SCMA transceiver are introduced in detail, and the message passing algorithm (Message Passing Algorithm, for receiver detection is also introduced in detail. The basic idea and operation principle of MPA are explained in detail. In this paper, several common SCMA codebook design ideas are presented, which are mainly used in the design of SCMA codebook mother constellation. By comparing the physical layer model of SCMA, the similarity and difference of SCMA uplink / downlink are given. The analysis of SCMA system capacity has always been one of the difficult issues. We have solved the related problems to some extent by analyzing its cut-off rate. The cut-off rate can be regarded as the lower limit of the system capacity, can be used to characterize the system reliability, and can be used to judge the system performance of different SCMA codebooks. This paper introduces the cut-off rate of the typical system and its important parameters, and further applies it to the analysis of the SCMA system. In order to improve the accuracy of cut-off rate analysis for SCMA systems, this paper presents an analysis method based on cloud segmentation (CloudPartition,CP), which is suitable for SCMA downlink. On this basis, the cut-off rate of SCMA downlink based on AWGN and Rayleigh is analyzed theoretically. Through the simulation results, the practicability and accuracy of the relevant theoretical derivation are verified.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5
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