双层异构网络中软频率复用技术的研究

发布时间：2018-02-21 00:34

本文关键词： 异构网络毫微微基站软频率复用频谱利用率图着色　出处：《上海师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：异构移动通信网络是一种在现有移动蜂窝通信系统的宏基站的覆盖范围内,引入低功率节点,如毫微微(Femto)基站、微微(Pi co)基站、中继节点(Relay),从而使网络的覆盖范围、系统容量得到改善的多层网络。其中,毫微微基站是一种适用于室内环境的超小型基站,不仅可以为室内移动用户提供更高的数据速率,还可以缓解宏蜂窝基站所存在的覆盖“盲点”问题。但现有的宏蜂窝网络与毫微微网络使用相同的频段,不仅使原本紧张的频谱资源更加捉襟见肘,而且使异构网中的同频干扰变得更为复杂。因此,在提高频谱效率的同时有效地控制小区间的同频干扰问题是研究中亟需解决的重点与难点。针对毫微微蜂窝网络与宏蜂窝网络所构成的双层异构网中频谱利用率以及同频干扰问题,本文将软频率复用技术(Soft Frequency Reuse,SFR)引入到毫微微蜂窝网络与宏蜂窝网络所构成的双层异构网场景中。在有效地控制小区间同频干扰的情况下为用户提供合适的频谱接入策略,提升频谱利用率,增加网络用户的吞吐量。主要研究内容如下:本文首先在固定SFR方案的基础上,针对固定SFR算法不能根据小区边缘负载情况对资源分配进行调整从而导致边缘用户吞吐量下降的问题,给出了一种动态的SFR方案。该方案联合采用接收信号强度值判断法和接收功率判断法对用户进行分类,并根据各宏小区边缘区域的负载情况来调整频谱的配置,不再使用原方案中固定的分配模式,从而达到缓解系统负担边缘用户的通信压力,并提高边缘频谱利用率的性能。针对FBS密集部署的双层网络场景下网络间的同频干扰问题,将遗传算法和图着色算法相结合,给出一种自适应SFR方案。该方案首先采用遗传算法获取小区中心区域的最优半径,然后采用图着色算法对小区边缘区域中的FBS进行分簇处理,最后根据每个簇中FBS的数量,自适应地为每个簇进行资源分配。仿真结果显示,该算法在控制小区间同频干扰的同时,提高了边缘区域的吞吐量,还降低了用户的平均中断概率。
[Abstract]:Heterogeneous mobile communication network is a kind of low power node, such as femto base station, picoco) base station and relay node, which is used in the coverage of the macro base station of the existing mobile cellular communication system, so that the network can be covered. A multilayer network with improved system capacity. Among them, the femto base station is a subminiature base station suitable for indoor environment, which can not only provide a higher data rate for indoor mobile users, It can also alleviate the problem of "blind spot" coverage in macrocellular base stations. However, the existing macrocellular networks use the same frequency band as the femto networks, which not only make the previously strained spectrum resources more stretched, Moreover, the cofrequency interference in heterogeneous networks becomes more complicated. It is an important and difficult problem to control the interference of the same frequency in the cell while improving the spectral efficiency. Aiming at the spectrum efficiency of the double layer heterogeneous network composed of the femto cellular network and the macro cellular network, it is necessary to solve the problem. And the problem of co-frequency interference, In this paper, soft Frequency reuse (SFR) technique is introduced to the two-layer heterogeneous network scene of femto cellular network and macro cellular network. It provides a suitable spectrum access strategy for the user under the condition of effectively controlling the interference of the same frequency in the cell. The main contents of this paper are as follows: firstly, on the basis of fixed SFR scheme, In view of the problem that the fixed SFR algorithm can not adjust the resource allocation according to the condition of the cell edge load, which leads to the decline of the throughput of the edge users. In this paper, a dynamic SFR scheme is presented, which combines the received signal strength judgment method and the receiving power judgment method to classify the users, and adjusts the spectrum configuration according to the load condition of the edge region of each macro cell. No longer using the fixed allocation mode in the original scheme, so as to relieve the communication pressure of the system under the edge users and improve the performance of the edge spectrum efficiency. Aiming at the co-frequency interference problem between the networks under the two-layer network scenario with intensive deployment of FBS, this paper proposes a new method to solve the problem. By combining genetic algorithm with graph coloring algorithm, an adaptive SFR scheme is proposed. Firstly, genetic algorithm is used to obtain the optimal radius of the center region of the cell, and then the graph coloring algorithm is used to cluster the FBS in the edge region of the cell. Finally, according to the number of FBS in each cluster, each cluster is allocated resources adaptively. The simulation results show that the algorithm not only controls the interference of the same frequency in each cell, but also improves the throughput of the edge region. It also reduces the average outage probability of the user.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

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