异构小蜂窝网络移动性管理研究综述

新一代移动通信网络不断演进为高密集、无定型、立体分层的异构网络，移动性管理旨在保证用户设备（user equipment，UE）移动通信服务的连续性和无缝切换及降低信令开销等。移动性管理问题正成为异构小蜂窝网络（heterogeneous and small cell networks，HetNets）中无线资源管理需要应对的关键性挑战之一。阐述了移动性管理的一般性问题，根据移动性管理的主要特征给出了一个综合分类：整体切换性能增强、小蜂窝发现与识别增强和无线链路失效（radio link failure，RLF）恢复增强。此外，依据此分类对近年来第三代合作伙伴计划（3rd genera-tion partnership project，3GPP）成员在无线接入网（radio access network，RAN）标准化工作组历次会议中提出的主要移动性管理增强方案进行了分类阐述和性能对比。对异构小蜂窝网络的移动性管理所面临的挑战和未来研究的趋势进行展望，并在此基础上进行了总结。

Survey of mobility management in heterogeneous and small cell networks

The next-generation mobile communication networks have been evolving into high dense, amorphous and heterogeneous networks, and mobility management (MM) is becoming one of RRM''s key challenges in heterogeneous and small cell networks (HetNets). MM aims to achieve continuity and seamless handover of UE mobile communications services and reduce signaling overhead, etc. In this paper, we describe the general problem of mobility management. Based on the key aspect of mobility management, a comprehensive classification of mobility management is provided subsequently, with the following three classes: improving overall handover performance, improving small cell discovery / identification, and improving the performance of radio link re establishment. In addition, we present a detail overview and comparison for mobility management enhancement schemes which were proposed by 3GPP members inrecent years. Finally, existing problems and open research issues are highlighted and a summary of the present study is given.