LTE-A数字中继随机接入的研究

发布时间：2018-01-10 10:11

本文关键词：LTE-A数字中继随机接入的研究　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：作为第四代移动通信系统,LTE-A提出了中继传输关键技术,不但优化了城市热点区域,而且扩展了盲区、地铁和农村的小区覆盖范围。不论中继接入基站还是用户接入中继,都必须先进行随机接入过程,所以提高随机接入的性能能够提高无线通信系统的整体性能。本文首先介绍了中继随机接入研究的背景知识和基本概念,接着详细分析了MAC层随机接入的处理过程。针对LTE-A系统内中继的MAC层随机接入处理过程不全面,接入时延大,碰撞率高等问题设计了MAC层功能架构和三种MAC层随机接入的算法机制,具体工作如下:1.为了提高中继随机接入的性能,本文在3GPP协议的基础上设计了RN的MAC层随机接入功能架构和处理过程,包括中继作为用户的上行接入和中继作为基站对接入处理的功能架构。2.针对RN接入施主基站的现有方案,即RN必须执行两次随机接入过程才能正式接入基站。本文提出了针对中继的直接随机接入过程,不但降低了中继的接入时延,而且提高了中继的接入概率。3.针对系统过载的情况,提出了基于重传的前导码分配方案,将新生成用户和重传用户使用的前导码分成两组,以提高重传用户的接入概率,降低用户的平均接入次数。4.针对现有的GB退避算法存在未考虑用户公平性的问题,本文提出了NGB算法。该算法考虑了用户的接入次数,提高了用户间的公平性。本文设计了RN的MAC层随机接入功能架构,提出了三种MAC层随机接入的算法机制,并进行了C++仿真和性能分析。
[Abstract]:As a 4th generation mobile communication system, LTE-A puts forward the key technology of relay transmission, which not only optimizes urban hot spots, but also expands blind areas. Whether the relay access base station or the user access relay, must first carry on the random access process. Therefore, improving the performance of random access can improve the overall performance of wireless communication systems. Firstly, this paper introduces the background knowledge and basic concepts of relay random access research. Then the processing process of random access in MAC layer is analyzed in detail. The random access process of MAC layer in LTE-A system is not comprehensive and the access delay is large. In order to improve the performance of relay random access, the functional architecture of MAC layer and three algorithms for random access in MAC layer are designed for the problem of high collision rate. The specific work is as follows: 1. Based on the 3GPP protocol, this paper designs the RN MAC layer random access function architecture and processing process. It includes the uplink access of the relay as the user and the functional architecture of the relay as the base station access processing. 2. The existing scheme for the RN access donor base station. That is, RN must perform two random access processes to formally access the base station. This paper proposes a direct random access process for relay, which not only reduces the relay access delay. Moreover, the access probability of relay is improved. 3. In view of the overload of the system, a preamble allocation scheme based on retransmission is proposed. The preamble codes used by the new generation user and the retransmission user are divided into two groups. In order to improve the access probability of retransmission users and reduce the average access times of users. 4. Aiming at the existing GB Backoff algorithm, there is a problem that the fairness of users is not considered. In this paper, NGB algorithm is proposed, which considers the number of users' access and improves the fairness between users. This paper designs the MAC layer random access function architecture of RN. Three algorithms for random access in MAC layer are proposed, and C simulation and performance analysis are carried out.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

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