【作者】 张宏；

【导师】 许威；

【作者基本信息】 东南大学 ， 信息与通信工程， 2015， 硕士

【摘要】 随着无线通信网络数据业务的爆发式增长,传统网络架构由于自身的局限性,已经无法满足未来无线通信网络中高用户密度、高数据速率的需求,新型无线网络架构的出现成为必然趋势。在这种形势下,3GPP在LTE-A的标准化进程中提出了异构网络的概念。异构网络的引入可以有效提高小区的频谱利用率和数据传输速率,但同时也面临着严重的小区间干扰问题。论文针对最新的异构网场景中的同频干扰问题,提出了新的上下行干扰协调技术,并通过仿真对不同的干扰协调技术进行了详细地对比和分析。论文首先介绍了移动通信网络的发展历程,然后重点讨论了LTE-A异构网络的背景和不同异构网场景中存在的干扰问题,对3GPP现有的异构网上行干扰协调技术和下行干扰协调技术进行详细地描述,并总结了现有各种干扰协调技术的优缺点。针对异构网不同场景中的干扰问题,论文第三章提出了改进的干扰协调技术。对于异构网上行宏小区和微小区同频覆盖场景,论文分别提出了基于用户分组的集中式资源分配技术和分布式用户专用功率控制技术,仿真结果显示论文提出的算法对异构网上行系统的边缘用户速率和平均用户速率都有明显地提升。对于宏小区和小蜂窝非同频覆盖的异构下行密集小蜂窝场景,论文提出了一种小蜂窝动态分组技术,仿真结果表明该技术对于密集小蜂窝场景下的干扰抑制效果随着小蜂窝数量的增加越来越明显。论文第四章基于3GPP技术报告TR 36.872中定义的最新异构网场景搭建了LTE-A异构网下行系统级仿真平台。论文详细阐述了该系统级仿真平台各个功能子模块的设计和实现,对仿真平台的核心模块主循环的设计流程进行了详细地介绍,并给出了主循环中接收用户反馈模块的设计流程图。为了便于系统级仿真平台的整体参数设置和仿真不同场景下异构网络的系统级性能,论文在该异构网系统级仿真平台上进一步添加了图形用户界面,对仿真平台各级参数设置界面进行详细地介绍。论文中给出了仿真平台在不同仿真阶段的中间输出结果图例,包括宏小区扇区方向性天线增益图、宏小区用户和小蜂窝用户的中间结果对比曲线图等。基于上一章搭建的LTE-A系统级仿真平台,论文第五章通过该平台仿真比较了异构网场景1和场景2a的系统性能、场景1中小蜂窝不同下行发射功率以及不同CRE偏置下的性能表现。论文基于该系统级仿真平台重点研究了异构网中的频率复用技术,比较了仿真平台在实现该频谱分配方案时涉及的关键系统参数(包括SINR门限值、频谱分配比例以及下行功率比)对异构网系统性能的影响。仿真结果表明在异构网场景1中用户负载不大的情况下,采用合适的频谱复用方案可以对小区边缘用户性能提升约5%～10%。更多还原

【Abstract】 In order to meet the demand of explosive growth of wireless communication data rate and higher quality of network coverage, the traditional network architecture has been unable to meet the requirements because of its own limitations. A new wireless network architecture has emerged as an inevitable trend. In this situation, 3GPP proposed heterogeneous networks in the standardization process of LTE-A. In heterogeneous networks, cell spectrum efficiency and transmission date rate are effectively improved, while facing a challenge of inter-cell interference suppression. To mitigate the interference, the thesis conducuted computer simulations for interference cancellation evaluation in different heterogeneous network scenarios and proposed several inter-cell interference coordination (ICIC) techniques of uplink and downlink.Firstly, the thesis introduces the development of mobile communication networks. The background and interference problems of LTE-A heterogeneous networks are described in detail. We focus on the existing uplink and downlink ICIC techniques and summarize the pros and cons of different ICIC techniques.The third chapter proposes improved ICIC techniques to mitigate the interference in different scenarios of heterogeneous networks. For uplink heterogeneous networks, we propose two ICIC schemes:a user-specific joint power control and resource allocation scheme and a dynamic user-specific power control scheme. Sim-ulation results verified that average user rates and edge user rates are significantly improved by the proposed schemes. In downlink dense small cell networks (SCN), a dynamic grouping based ICIC scheme is proposed. Simulation results show that the improvement of system performance becoms more pronounced when there are more small cells in the network.The fourth chapter constructs a downlink system-level simulator in LTE-A heterogeneous networks based on 3GPP TR 36.872. The paper elaborates the design and implementation of each functional mod-ule of the simulator. We introduce the design process of the main loop and provide the design flow of the feedback receiving module. We also add a graphic user interface (GUI) for the simulator in order to facilitate the parameter setting under different scenarios. In addition, the paper provides several simulation outputs, including directional antenna gain of macrocell sector, performance comparison of macrocell UEs and small cell UEs.Finally in chapter five, we compare the system performance of scenario 1 and scenario 2a by our con-ducted system-level simulator. The performance of different small cell transmission power in the downlink and different CRE biases are also compared by the simulator. In addition, the paper studies the frequency reuse schemes based on the system-level simulator. Key parameters of the frequency reuse schemes, includ-ing SFNR threshold, spectrum ratio and downlin power ratio, are tested for comparison in the simulator as well. Simulation results show that the performance gain of the frequency reuse schemes is about 5%～10% in scenario 1 when the user load is not heavy.更多还原