The future 5th generation (5G) mobile communication system will be required to support diverse services. Because of the difficulty in addressing the requirements of all these services using the same physical network, ''network slicing,'' which provides a customized logical network corresponding to service requirements, has recently attracted a great deal of attention. In the radio access network (RAN), the appropriate locations of base station functionalities to meet service requirements and achieve efficient network operation differ according to service type. Therefore, we have proposed a novel RAN slicing architecture, which has logical networks (slices) that choose an appropriate functional split option and its placement, to adjust to providing any service. This architecture achieves high flexibility and large scalability by employing a software-defined network and network function virtualization. A prototype is then developed based on the proposed architecture employing a unified controller of open-source software. It can construct slices for three service types: enhanced mobile broadband, ultra-reliable and low-latency communication, and massive machine-type communication, with flexibly located functionalities. In this paper, an experimental evaluation, considering the points of bandwidth consumption in midhaul, the impact of midhaul delay, communication latency, and isolation among slices, shows that the slices have specific performance benefits for each service type and also to achieve efficient network operation. This suggests that the proposed architecture is able to construct slices in a single infrastructure with different features according to the services required and to accommodate various services efficiently. INDEX TERMS 5G mobile communication, software-defined network, network function virtualization RAN slicing, functional splits. I. INTRODUCTION A. GENERAL BACKGROUND Recently, research and development have been actively pursued in the future 5th generation (5G) mobile network. 5G is expected to support diverse services such as highdefinition video distribution, autonomous driving, remotecontrolled robots and the Internet of Things (IoT) [1], and the services are classified roughly into three types; enhanced mobile broadband (eMBB), ultra-reliable and lowlatency communication (URLLC), and massive machine-type communication (mMTC) [2]. The associate editor coordinating the review of this manuscript and approving it for publication was Xiaodong Xu.
