摘要
随着移动通信技术的发展,用户业务量和数据吞吐量不断增加,第三代移动通信系统已不能完全满足用户的需求。因此,3GPP致力于研究3GPP LTE (Long Term Evolution)作为3G系统的演进。在LTE标准接近于完成之时,一个在LTE基础上继续演进的项目——先进的LTE(LTE-Advanced)项目又在3GPP拉开了序幕。随着3GPP中针对LTE-Advanced的讨论逐渐展开,3GPP产业界对LTE-Advanced的需求和技术演进的看法也渐趋明朗。在LTE到LTE-Advanced系统的演进过程中,更宽频谱的需求将会成为影响演进的最重要因素之一,为此3GPP提出了载波聚合技术。
本文在查阅和参考大量资料的基础上,首先介绍了LTE-Advanced演进过程、需求和主要技术特点,然后重点描述了载波聚合技术的原理和研究重点,主要包括载波聚合的方式、传输块的映射方式、控制信道的设计以及调度结构的设计等。
为了很好地评估系统性能,我们基于c++语言搭建了LTE动态平台,以快照法构成仿真方法的框架,在每次快照中,再结合时间驱动法获得所需的系统性能的统计。该仿真平台针对载波聚合和独立载波进行下行链路仿真,实现了载波聚合支持的两种调度结构,以及Full Buffer、Finite Buffer、Burst业务模型和多天线模型。本文详细介绍了平台的仿真流程和主要功能模块的实现过程,并且分别在不同场景下研究了载波聚合技术对系统性能的提升,并给出了相应的仿真结果和分析。
With the development of mobile communication and the increasing of user number and date rate,3G system can't satisfy the requirement of users. So 3GPP devotes the study of LTE (Long Term Evolution) as the evolution of 3G system. And then 3GPP came up with LTE-Advanced, which can support backward-compatibility. With the discussion of LTE-Advanced in 3 GPP meeting, the options of the requirement and technology evolution become more and more mature. In the process of the evolution from LTE to LTE-Advanced, the requirement of wider bandwidth is one of the most important factors that affect the evolution, so 3GPP proposed carrier aggregation technology.
On the basis of studying a large amount of relevant theories, this thesis firstly introduces the evolution of LTE and LTE-Advanced, the requirements and the technical features, and then it focuses on the theory and study of carrier aggregation, including the methods of carrier aggregation, the mapping transport block and the design of control channel and scheduling structure.
In order to evaluate the performance of carrier aggregation, the whole simulation platform is implemented with C++ programming language, which framework is implemented based snapshot method. In each snapshot, the system performance statistician is achieved by time driving method. And then the platform achieved the downlink simulation of carrier aggregation and independent carrier respectively and achieved the two scheduling structures supported carrier aggregation, three traffic models (Full Buffer, Burst, and Finite Buffer) and multiple antenna technology. The simulation process and implement of function modules are detailed described in the thesis. The simulation in different scenarios mainly focuses on the performance enhancement of carrier aggregation and finally presents simulation results.
引文
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