LTE-A异构网络中的干扰协调机制研究

发布时间：2018-01-29 02:57

本文关键词： LTE-A 异构网络小区间干扰协调覆盖增强几乎全空子帧随机几何泊松点过程　出处：《中国科学技术大学》2014年博士论文　论文类型：学位论文

【摘要】：随着移动互联网的快速发展,用户对数据业务的需求日益增强。在线游戏、视频通话、高速下载等应用对蜂窝网络的速率和延迟等性能要求越来越高。另一方面,有统计资料表明未来2/3的电话和90%以上的数据业务是在室内发生。然而由于信号的穿墙损耗,宏蜂窝网络很难保证室内用户的速率需求。因此,3GPP (3rd Generation Partnership Project)组织在LTE (Long Term Evolution) Release10版本中引入了低功率节点,用于拉近用户和基站间的距离,从而提升用户吞吐量。这种在宏蜂窝网络中叠加低功率节点的网络架构被称为异构网络(Heterogeneous Networks, HetNets)。为了最大化频谱利用率,3GPP倾向于采用同频组网方式。宏基站之间、低功率节点之间的同层干扰和宏基站与低功率节点之间的跨层干扰成为了制约异构网络性能的关键因素。相比于传统宏蜂窝网络,低功率节点具有部署随机、封闭用户接入、覆盖增强等技术特点,使得异构网络的干扰情况尤其复杂。因此,LTE-A异构网络的小区间干扰协调技术对异构网络具有重要意义。本文以Macro-Femto网络和Macro-Pico网络为例,对异构网络的小区间干扰协调技术进行了系统性的研究。主要贡献和创新点如下： 1)研究Macro-Femto异构网络中的下行干扰问题,提出了一种基于干扰图的频域干扰协调方案。在干扰图建模中,图顶点为位于家庭基站干扰区域内的宏小区用户或家庭基站,边代表干扰关系,权重代表干扰程度。权重根据区域平均信道准则确定。将分簇问题建模为图论中最大K割问题,并提出一个启发式算法——基于干扰图的混合分簇方案(HCIG)来近似求解。HCIG方案能同时减弱Macro-Femto网络中的三种下行干扰,提高网络吞吐量。 2)研究Macro-Femto异构网络中的Femto之间的干扰问题,提出了一种基于家庭基站协作的干扰协调方案。在3GPP标准中,邻居家庭基站间存在X2接口,使得家庭基站间的协作变为可能。利用家庭基站间的辅助数据传输,本文提出一种名为虚切换的协作机制以消除邻居家庭基站间的干扰。虚切换的核心思想是将用户平面和数据平面进行分离。当虚切换发生时,控制信息由原始服务家庭基站承载,而数据信息由邻居干扰基站辅助传输。虚切换对用户和移动管理实体透明,只涉及家庭基站间的控制信令交互。并且信息交互是通过有线X2链路,因此该方案开销低、成功率高。 3)研究Macro-Pico异构网络中的宏基站对Pico用户的干扰问题,分析基于ABS (Almost Blank Subframe)的时域干扰协调方案中ABS比例的设置问题。采用覆盖增强技术时,宏基站会对Pico扩展覆盖范围内的用户造成较强的下行干扰。通常采用基于ABS的时域干扰协调来消除此类干扰。本文利用泊松点过程网络模型分析了在采用覆盖增强技术下的Macro-Pico网络的性能,得到用户到服务基站的距离分布、用户的SIR分布、用户的平均吞吐量。在此基础上,分析了在给定覆盖增强偏置值时ABS比例的合理取值范围。该工作对实际网络中覆盖增强偏置值和ABS比例的设置具有一定的参考意义。 4)研究Macro-Pico异构网络中的覆盖增强机制对用户中断概率的影响,提出一种负载感知的泊松点过程网络模型。注意到传统泊松点过程网络模型没有考虑基站的实际负载,而只是简单假设基站满负载,本文将基站负载和按需资源分配方案加入到传统泊松点过程模型中,得到更加接近实际情况的负载感知的干扰分析模型。利用该模型分析Macro-Pico网络中覆盖增强机制对用户中断概率的影响,分析得到在给定覆盖增强偏置时用户中断概率的表达式。 5)研究Macro-Pico异构网络中的宏基站和Pico基站间的干扰问题,提出一种负载自适应的干扰协调方案。为了使得Pico能够更好地为热点用户提供通信资源,本文提出一种基于热点区域的有界覆盖增强方案来扩大Pico的覆盖范围。基于有界覆盖增强方案,进一步提出了负载自适应的动态覆盖控制算法来实现宏基站和Pico基站间的负载均衡,并提出混合时频域干扰协调算法来减轻宏基站对Pico扩展覆盖范围内的用户的干扰。负载自适应的动态覆盖控制算法及混合时频域干扰协调算法能够在用户QoS保证和网络容量之间实现较好的折衷。
[Abstract]:With the rapid development of mobile Internet, the user demand for data services is increasing. Online games, video calls, high-speed download rate requirements for applications such as cellular network and delay performance is more and more high. On the other hand, statistics show that the future of 2/3 phone and more than 90% of the data service is in the interior. However because the wall loss of signal, the macro cellular network is very difficult to guarantee the rate of demand of indoor users. Therefore, 3GPP (3rd Generation Partnership Project LTE (Long) in Term Evolution) low power node into the Release10 version, for users and to narrow the distance between the base station, so as to enhance the user throughput. This is superimposed on the macro cellular network in low power node network architecture called heterogeneous network (Heterogeneous Networks, HetNets).
In order to maximize the utilization of the spectrum, 3GPP tend to use the same frequency network. Acer station, between the same layer interference between low power node and Acer station and low power node cross layer interference has become a key factor restricting the performance of heterogeneous network. Compared to the traditional macrocell network, low power nodes are deployed randomly. Closed user access, coverage enhancement technique, the interference of the heterogeneous network is particularly complex. Therefore, LTE-A heterogeneous networks, inter cell interference coordination technology has important significance for heterogeneous network. Based on the Macro-Femto network and Macro-Pico network as an example, the interference coordination technology in heterogeneous network between cells were systematically studied. The contribution and innovation are as follows:
1) the problem of downlink interference in Macro-Femto isomeric networks is studied, and a frequency domain interference coordination scheme based on interference graph is proposed.
In the interference graph modeling, graph vertex in femtocell interference region of the macrocell users or home base stations, the edges represent interference, interference degree of weight weights according to the regional representative. The average channel criterion. The clustering problem is modeled as a graph K maximum cut problem, and propose a heuristic algorithm based on hybrid the interference graph clustering scheme (HCIG) to approximate the.HCIG scheme can decrease three downlink interference in Macro-Femto network, improve the network throughput.
2) the interference problem between Femto in Macro-Femto isomeric networks is studied, and a interference coordination scheme based on the collaboration of home base station is proposed.
In the 3GPP standard, the X2 interface between the neighbor home base station, family collaboration between base stations is possible. The use of auxiliary data transmission between the home base station, this paper proposes a mechanism called collaborative virtual switch to eliminate the interference between neighbor home base station. The core thought of virtual switching is separated from the user plane and the data plane. When a virtual switch occurs, the control information carried by the original service home base station, and the data information from neighbor interference base station assisted transmission. The virtual switch transparent to the user and the mobile management entity, involving only the control signal between the base stations to family interaction. And the information interaction is through the wired X2 link, so the scheme of low cost the success rate is high.
3) study the interference of macro base stations to Pico users in Macro-Pico heterogeneous network, and analyze the setting of ABS ratio based on ABS (Almost Blank Subframe) in the time domain interference coordination scheme.
The coverage enhancement technique, Acer station will cover the range of users caused by downlink interference on strong Pico expansion. Usually by the time domain interference coordination based on ABS to eliminate such interference. Using the Poisson point process model analysis in the network coverage performance enhancement technology under the Macro-Pico network, users get to the distance distribution service station the distribution of SIR users, the average user throughput. Based on the analysis of the coverage enhancement reasonable range of bias value ABS in a given proportion. This work on the actual network coverage enhancement bias value and the ratio of ABS set has certain reference significance.
4) to study the influence of the coverage enhancement mechanism in the Macro-Pico heterogeneous network on the interruption probability of the user, a load aware Poisson point process network model is proposed.
Pay attention to the actual load of traditional Poisson point process network model without considering the base station, but simply assume that the base station base station full load, load and on-demand resource allocation scheme is added to the traditional Poisson point process model, the interference is more close to the actual situation of the load sensing model. Mechanism analysis of impact on the user outage probability coverage the enhanced Macro-Pico network by using the model analysis of coverage enhancement bias user outage probability in a given expression.
5) to study the interference between the macro base station and the Pico base station in the Macro-Pico heterogeneous network, and propose a load adaptive interference coordination scheme.
In order to enable the Pico to provide better communication resources for hot users, this paper proposes a method based on hot region bounded coverage enhancement scheme to expand the coverage of Pico. Based on the bounded coverage enhancement scheme, further proposes a dynamic load adaptive coverage control algorithm to achieve load balancing between Acer and Pico base station, and put forward mixed frequency time domain interference coordination algorithm to reduce the interference range of Acer station expansion of users on Pico. The dynamic load adaptive coverage control algorithm and mixed frequency time domain interference coordination algorithm can guarantee the QoS between user and network capacity to achieve a good tradeoff.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.5

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