稀疏码多址接入以及在MIMO系统中的应用

发布时间：2018-06-09 22:40

本文选题：SCMA + 码本分配　；参考：《电子科技大学》2017年硕士论文

【摘要】：随着无线通信技术的飞速发展,传统的正交多址接入已经不能满足海量用户接入的需求。非正交多址接入技术作为第五代移动通信的备选多址方案,由于可以在相同的时频资源上复用更多的用户数据而备受瞩目。稀疏码多址接入(Sparse Code Multiple Access,SCMA)就是非正交多址技术的一种。在发送端,SCMA将比特数据直接映射为从预先设定的码本中选择出来的复多维码字,不同层的码字在相同的资源上以稀疏扩频的方式进行非正交叠加;在接收端,利用码字的稀疏性对用户数据进行联合检测,然后通过信道译码解调出相应的比特数据。与正交多址相比,SCMA可以在相同的时频资源的情况下,极大地提高系统频谱效率。本文首先介绍了SCMA的基本编码原理和一些关键技术,包括SCMA编码和复用方式、SCMA多维码本的设计、接收端经典的检测算法,并对两种经典的检测算法进行了仿真对比。其次,基于以上研究给出了上行系统容量。在此基础上,针对容量最大化的码本和功率分配问题,介绍了一种基于信道状态信息的码本分配方案,但是该方案并没有考虑用户间干扰信息的影响。本文将用户间的干扰信息动态地考虑到分配过程中,提出了一种基于容量最大化的码本分配和功率分配方案,并且与几种经典分配方案进行仿真对比,仿真结果表明本文所提方案可以进一步提高系统容量。最后,针对下行多用户多输入多输出(Multiple Input Multiple Output,MIMO)系统,本文对SCMA与多用户MIMO系统的结合进行了研究。基于非正交多址接入(Non-Orthogonal Multiple Access,NOMA)在MIMO系统下的分簇模型,建立了SCMA系统的分簇模型并给出了系统容量;针对减少用户簇间干扰和提高系统容量的目标,介绍了两种簇间预编码方案和一种基于信道相关性的用户分簇方案,但是该分簇方案只适用于信道相关性高且每个簇中只有两用户的情况;提出了一种适用于相关信道用户和非相关信道用户的改进分簇方案,该方案不仅降低了分簇的复杂度,而且对每个簇多个用户的情况同样适用。
[Abstract]:With the rapid development of wireless communication technology, traditional orthogonal multiple access can not meet the needs of mass access. As an alternative multiple access scheme for the fifth generation mobile communication, non-orthogonal multiple access (NOAA) technology has attracted much attention for its ability to reuse more user data on the same time-frequency resources. Sparse code multiple access (Sparse Code multiple access) is one of the non-orthogonal multiple access technologies. At the sending end, the SCMA maps the bit data directly to the complex multi-dimensional codewords selected from the preset codebook. The different layers of codewords are superposed in a sparse spread spectrum manner on the same resources; at the receiving end, The code-word sparsity is used to detect the user data, and the corresponding bit data is demodulated by channel decoding. Compared with orthogonal multiple access, SCMA can greatly improve the spectral efficiency of the system with the same time-frequency resources. This paper first introduces the basic coding principle and some key technologies of SCMA, including the design of SCMA multi-dimensional codebook and multiplexing mode, the classical detection algorithm on the receiving end, and makes a simulation comparison between the two classical detection algorithms. Secondly, the uplink system capacity is given based on the above research. On this basis, a codebook allocation scheme based on channel state information is proposed for the codebook and power allocation problem with maximum capacity, but the influence of interference information between users is not taken into account in this scheme. In this paper, the interference information between users is dynamically taken into account in the allocation process, and a codebook allocation and power allocation scheme based on maximum capacity is proposed and compared with several classical allocation schemes. Simulation results show that the proposed scheme can further improve the system capacity. Finally, the combination of SCMA and MIMO system is studied in this paper for the downlink multi-user multiple-input multiple-output (MIMO) system. Based on the clustering model of Non-orthogonal multiple access (NOAA) in MIMO system, the clustering model of SCMA system is established and the system capacity is given. This paper introduces two precoding schemes and a user clustering scheme based on channel correlation, but this scheme is only suitable for those with high channel correlation and only two users in each cluster. An improved clustering scheme for both correlated and uncorrelated channel users is proposed. This scheme not only reduces the complexity of clustering, but also applies to the case of multiple users per cluster.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.3

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