曾菊玲 夏凌 解冰 张春雷

【摘  要】通过分析MBSFN系统结构，提出了C-RAN及CU/DU分离环境下的MBSFN网络切片架构，对切片的基础设施与虚拟网络划分、基于CU//DU分离的协议及信道划分、主要通信过程以及切片的功能实体和性能做了详细讨论。基于提出的CU-DU-RRU三层可重配切片架构，提出了一种低代价的基于距离的位置更新机制，将MCE控制的小区列表更新TAL转变为MCE辅助的RRU控制、基于距离测量的搜索和更新，克服了MCE完全控制导致的搜索次数和信令开销较大的缺点。建立MARKOV模型对机制进行了性能分析，仿真表明，在搜索次数和信令开销两方面均优于LTE中的TAL机制，进而说明所提出的MBSFN网络切片架构的合理性。

【关键词】C-RAN及CU/DU分离;MBSFN;网络切片;协议分割;基于距离的位置更新

By analyzing the MBSFN system structure， this paper proposes a three-layer reconfigurable architecture of MBSFN network slice in the C-RAN and CU/DU separation environment. The division between slice infrastructure and virtual network， the partition of CU/DU separation-based protocol and the allocation of logical channel， the main communication process， the functional entities and performance of slices are discussed in detail. Based on the CU-DU-RRU three-layer reconfigurable slice architecture in this paper， a low-cost distance-based location updating strategy is proposed. Searching user and updating location in this strategy is done by RRU and aided by MCE based on the distance changed from the cell listing， which avoid the more searching times and bigger overhead resulted by MCEs only finishing all that. The performance of this strategy is addressed based on MARKOV link. The simulation results shows that the mechanism is better than the time-based TAL mechanism in LTE，in searching times and signaling overheads.. This demonstrate the MBSFN slice framework in this paper is reasonable.

C-RAN and CU/DU sepration; MBSFN; network slice; protocol partition; distance-based location updation

0   引言

隨着5G的发展，流媒体业务以及面向物联网的订阅业务越来越多，基于应答确认式的点对点单播通信方式已经不能满足要求，以较少资源为大量具有相同需求的用户同时提供业务的高效MBMS（多媒体广播/组播业务）技术越来越得到重视[1]。

蜂窝移动通信中的MBMS最初由3GPP在R6、R7版本中提出。eMBMS（enhanced MBMS）在R9中正式提出，引入MCE、MBMS GW、BM_SC等新的网络功能实体以提供对eMBMS业务的支持。同时，在接入网中还定义了MBSFN（多播广播单频网）传输模式，MBSFN由于同时同频在多个小区进行MBMS业务的同步传输，不仅提高了系统频谱效率，而且能利用相邻小区干扰信号，产生分集效应和提高盲区覆盖率，得到了广泛研究。文献[2]、[3]研究了MBSFN的资源分配以及区域形成，文献[4]对基于MBSFN的集群通信系统业务连续性、移动性管理及越区切换进行了研究。……