SUMMARYWireless engineers and business planners commonly raise the question on where, when, and how millimeter-wave (mmWave) will be used in 5G and beyond. Since the next generation network is not just a new radio access standard, but also an integration of networks for vertical markets with diverse applications, answers to the question depend on scenarios and use cases to be deployed. This paper gives four 5G mmWave deployment examples and describes in chronological order the scenarios and use cases of their probable deployment, including expected system architectures and hardware prototypes. The first example is a 28 GHz outdoor backhauling for fixed wireless access and moving hotspots, which will be demonstrated at the PyeongChang Winter Olympic Games in 2018. The second deployment example is a 60 GHz unlicensed indoor access system at the Tokyo-Narita airport, which is combined with Mobile Edge Computing (MEC) to enable ultra-high speed content download with low latency. The third example is mmWave mesh network to be used as a micro Radio Access Network (µ-RAN), for cost-effective backhauling of small-cell Base Stations (BSs) in dense urban scenarios. The last example is mmWave based Vehicular-to-Vehicular (V2V) and Vehicular-to-Everything (V2X) communications system, which enables automated driving by exchanging High Definition (HD) dynamic map information between cars and Roadside Units (RSUs). For 5G and beyond, mmWave and MEC will play important roles for a diverse set of applications that require both ultra-high data rate and low latency communications. key words: millimeter wave, MEC, 28GHz, 60GHz, mesh network, V2V/V2X, automated driving, future forecast

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In recent years, the increasing traffic demand in radio access networks (RANs) has led to considerable growth in the number of base stations (BSs), posing a serious scalability issue, including the energy consumption of BSs. Optical-access-enabled Cloud-RAN (CRAN) has been recently proposed as a next-generation access network. In CRAN, the digital unit (DU) of a conventional cell site is separated from the radio unit (RU) and moved to the 'cloud' (DU cloud) for centralized signal processing and management. Each DU/RU pair exchanges bandwidth-intensive digitized baseband signals through an optical access network (fronthaul). Time-wavelength division multiplexing (TWDM) passive optical network (PON) is a promising fronthaul solution due to its low energy consumption and high capacity. In this paper, we propose and leverage the concept of a virtual base station (VBS), which is dynamically formed for each cell by assigning virtualized network resources, i.e., a virtualized fronthaul link connecting the DU and RU, and virtualized functional entities performing baseband processing in DU cloud. We formulate and solve the VBS formation (VF) optimization problem using an integer linear program (ILP). We propose novel energy-saving schemes exploiting VF for both the network planning stage and traffic engineering stage. Extensive simulations show that CRAN with our proposed VF schemes achieves significant energy savings compared to traditional RAN and CRAN without VF

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Current Radio Access Networks (RANs) need to evolve to handle diverse service requirements coming from the growing number of connected devices and increasing data rates for the upcoming 5G era. Incremental improvements on traditional distributed RANs cannot satisfy these requirements, so the novel and disruptive concept of cloud-RAN (CRAN) has been proposed to decouple digital units (DUs) and radio units (RUs) of base stations (BSs), and centralize DUs into a central office, where virtualization and cloud computing technologies are leveraged to move DUs in the "cloud". However, separating RUs and DUs requires low-latency and high-bandwidth connectivity links, called "fronthaul", as opposed to traditional backhaul links. Hence, design of the 5G transport network, i.e., the part of the network that carries mobile data traffic between BSs and the core network and data centers, is key to meet the new 5G mobile service requirements and effectively transport the fronthaul traffic. Today, consensus has not yet been achieved on how the fronthaul traffic will be transported between RUs and DUs, and how virtualization of network resources will occur from radio network segment to the centralized baseband processing units. In this article, we present a new 5G architecture called virtualized-CRAN (V-CRAN) moving towards a cell-less 5G network architecture. We leverage the concept of a "virtualized-BS" (V-BS) that can be optimally formed by exploiting several enabling technologies such as softwaredefined radio (SDR) and Coordinated Multi-Point (CoMP) Transmission/Reception. V-BS can be formed on a per-cell basis or peruser basis by allocating virtualized resources on demand. For the fronthaul solution, our approach exploits the passive optical network (PON), where a wavelength can be dynamically assigned and shared to form "virtualized" PON (VPON). Several use cases of V-CRAN are presented to show how network architecture evolution can enhance system throughput, energy efficiency, and mobility management.