LTE系统中MME负载均衡的研究

发布时间：2018-10-25 10:13

【摘要】：随着移动网络用户的增加,智能终端的普及和移动应用服务的的主流化,现在的移动通信已经呈现了爆炸性增长趋势。移动互联网业务和M2M(Machine to Machine)等新兴业务在给用户提供服务的同时,也给核心网信令控制带来很大的负担,容易造成信令在MME(Mobility Management Entity)出现阻塞从而导致网络整体性能下降。核心网控制网元MME的负载均衡功能可以实现若干MME之间的资源共享和负荷分担,从而有效预防网络中信令传输的阻塞。本文依托“基于TD-LTE的宽带移动专用通信网络总体方案与测试评估研究”国家科技重大专项,首先在第三章中针对MME软件实现的必要接口以及协议进行了研究分析,接着第四章对MME间的负载均衡算法进行了研究设计并进行仿真验证,通过前两章的准备第五章在实验系统中实现了MME软件的负载均衡功能。首先,本文对MME间的负载均衡算法进行了研究与设计。本文通过对MME性能影响因素的分析,筛选出UE附着数量以及承载激活数量作为衡量MME性能权重的主要因素,并通过数学建模设计出了MME权重计算的多准则表达式。在此基础上,对普通负载均衡方法中使用固定周期进行权重更新的做法进行了改进,设计出能够根据相邻周期内MME上用户数量的变化趋势而自适应调整下一次权重更新时间的负载均衡算法,缩小了对用户数量变化趋势的感知粒度,从而进一步提高MME的负载均衡能力。基于以上研究,本文对改进的负载均衡算法进行了仿真。仿真结果验证了改进后的算法提高了MME负载均衡性能,更加充分地利用了MME资源。在MME负载均衡算法设计的基础上,文章结合项目需求在MME实验软件中实现了负载均衡功能。基于在国家科技重大专项中对MME实现技术的研究,本文对OpenAirInterface 4G开源项目中的MME实验软件进行改进,通过添加统计功能、MME权重计算功能、相关消息定义以及MME配置更新的交互过程,实现了MME的负载均衡功能。最后文章还对MME实验软件进行了测试,首先模拟搭建了一个简单的MME池,通过该测试环境对MME基本通信流程和MME负载均衡软件流程分别进行了功能测试,验证了MME实验软件负载均衡功能的有效性。
[Abstract]:With the increase of mobile network users, the popularity of intelligent terminals and the mainstream of mobile application services, mobile communication has shown an explosive growth trend. The new services such as mobile Internet service and M2m (Machine to Machine) service not only provide service to users, but also bring a great burden to the core network signaling control. It is easy to cause signaling blocking in MME (Mobility Management Entity), which leads to the deterioration of overall network performance. The load balancing function of the core network control network element (MME) can realize resource sharing and load sharing among several MME so as to effectively prevent the blocking of signaling transmission in the network. This paper relies on the "Research on the overall Scheme and Test Evaluation of Broadband Mobile Private Communication Network based on TD-LTE". Firstly, in Chapter 3, the necessary interfaces and protocols of MME software are studied and analyzed. In chapter 4, the load balancing algorithm between MME is designed and simulated. In the fifth chapter, the load balancing function of MME software is realized in the experimental system by the preparation of the first two chapters. Firstly, the load balancing algorithm between MME is studied and designed. Based on the analysis of the factors affecting the performance of MME, the number of UE attachment and the number of load-bearing activation are selected as the main factors to measure the weight of MME, and the multi-criteria expression for calculating the weight of MME is designed by mathematical modeling. On this basis, the method of using fixed period to update the weight in the ordinary load balancing method is improved. A load balancing algorithm which adaptively adjusts the next weight update time according to the changing trend of the number of users on the MME during the adjacent period is designed, which reduces the perceived granularity of the changing trend of the number of users. Thus, the load balancing ability of MME is further improved. Based on the above research, the improved load balancing algorithm is simulated in this paper. The simulation results show that the improved algorithm improves the load balancing performance of MME and makes full use of MME resources. Based on the design of MME load balancing algorithm, this paper realizes the load balancing function in MME experiment software combined with project requirements. Based on the research of the MME implementation technology in the important national science and technology project, this paper improves the MME experimental software in the OpenAirInterface 4G open source project, through adding the statistical function, the MME weight calculation function, The related message definition and the interactive process of MME configuration update realize the load balancing function of MME. Finally, the MME experimental software is tested. First, a simple MME pool is built, and the basic communication flow of MME and the MME load balancing software flow are tested by the test environment. The effectiveness of the load balancing function of MME experimental software is verified.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

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