NeTS: Small: Collaborative Research: Configuration Management for Mobility Support in Cellular Networks

移动支持被认为是下一代互联网的基础服务。目前的蜂窝网络是现实中唯一能够成功提供广域、无处不在的移动支持的大规模基础设施。随着智能手机设备的爆炸式增长和移动数据流量的激增，蜂窝网络已经演变成一个日益异构的网络系统。因此，管理流动性变得既具有挑战性，又有回报。本项目旨在研究2G/3G/4G网络的移动性管理配置问题，以确保理想的移动性支持。研究的重点是评估两种结构特性：稳定性和可达性。稳定性意味着在恒定的网络条件下没有持续的振荡回路，而可达性意味着没有接入黑洞（例如，设备无法到达某些蜂窝甚至给定的移动技术（例如，4G））。该项目的成功不仅将识别和描述当今蜂窝网络中的错误配置，而且还将保护快速扩展的移动信息基础设施中数万亿美元的投资。获得的结果可能会影响即将到来的5G无线网络的设计。拟议的研究有三个关键的技术贡献领域。首先，它采用了一种新颖的构型研究方法。它对有问题的案例进行建模和分析，并为移动性配置问题提出不稳定性和不可达性的分类，并为每个有问题的实例派生触发条件。其根本问题在于它的分布式配置决策，但没有很好地协调。第二，项目涵盖了从理论到实践的活动。考虑到在理论上发现的错误配置实例，它进一步在实际移动网络中进行经验评估。它试图衡量它们在现实中的可能性，并量化它们对用户设备和网络基础设施的负面影响。需要分析的根源多种多样，包括单个参数内的策略冲突、不同类型参数之间的不一致、设备与网络之间的决策不协调等。最后，提出了移动网络配置管理的新解决方案。本研究简化了目前的方法，同时保留了其参数的完全可配置性。为此，为了保证机动性支持的稳定性和可达性，探讨了决策规则复制最小化和无多跳机动性决策两种设计准则。

Mobility support is deemed a fundamental service for the next-generation Internet. The current cellular network is the only large-scale infrastructure that successfully provides wide-area, ubiquitous mobility support in reality. With the explosive growth of smartphone devices and the surge of mobile data traffic, cellular networks have been evolving into an increasingly heterogeneous networked system. As a result, managing mobility becomes challenging yet rewarding. This project seeks to study the configuration issues on mobility management of 2G/3G/4G networks, in order to ensure desirable mobility support. The research focuses on assessing two structural properties: stability and reachability. Stability implies no persistent oscillation loops during constant network conditions, while reachability denotes no access black hole (e.g., certain cells or even a given mobile technology (e.g., 4G) cannot be reached by the device). The success of the project will not only identify and characterize misconfigurations in today's cellular networks, but also protect multi-trillion dollar investment in the fast expanding mobile information infrastructure. The obtained results may influence the design of upcoming 5G wireless networks. The proposed research has three key areas of technical contributions. First, it takes a novel approach to configuration study. It models and analyzes problematic cases and comes up with a taxonomy of instability and unreachability for the mobility configuration problems, and derives triggering conditions for each problematic instance. The fundamental problem lies in its distributed, yet not well-coordinated configuration decision-making. Second, the project covers activities from theory to practice. Given the misconfiguration instances discovered in theory, it further empirically assesses them in operational mobile networks. It seeks to measure their likelihood in reality and quantify their negative impacts on both the user device and the network infrastructure. The diversified root causes are to be analyzed, spanning policy conflicts within a single parameter, inconsistency between different types of parameters, and uncoordinated decisions between the device and the network. Last, the research proposes new solutions to configuration management in mobile networks. This research simplifies the current approach, while retaining its full configurability for parameters. To this end, two design guidelines of minimal replication of decision rules and no multi-hop mobility decision are explored in order to ensure both stability and reachability of mobility support.