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Where, When, and How mmWave is Used in 5G and Beyon
Kei Sakaguchi, Thomas Haustein, Sergio Barbarossa, Emilio Calvanese Strinati, Antonio Clemente, Giuseppe Destino, Aarno Pärssinen, Ilgyu Kim, Heesang Chung, Junhyeong Kim, Wilhelm Keusgen, Richard J. Weiler, Koji Takinami, Elena Ceci, Ali Sadri, Liang Xain, Alexander Maltsev, Gia Khanh Tran, Hiroaki Ogawa, Kim Mahler, Robert W. Heath
TL;DR
The paper addresses limited discussion of the scenarios, use cases, and enabling technologies for deploying mmWave in diverse 5G networks. The paper introduces mmWave and MEC, then presents four deployment examples in chronological order with associated scenarios, architectures, and prototypes. The paper presents four 5G mmW use cases, including 28 GHz backhaul for moving hotspots during the 2018 PyeongChang Winter Olympics.
Problem
The paper addresses limited discussion of the scenarios, use cases, and enabling technologies for deploying mmWave in diverse 5G networks.
Method
The paper introduces mmWave and MEC, then presents four deployment examples in chronological order with associated scenarios, architectures, and prototypes.
Results
The paper presents four 5G mmW use cases, including 28 GHz backhaul for moving hotspots during the 2018 PyeongChang Winter Olympics.
Takeaways & Limitations
mmWave and MEC are positioned for diverse 5G and beyond applications requiring both ultra-high data rates and low-latency communications.
Takeaways & Limitations
mmWave links can experience channel intermittency from blockage or interference, motivating multilink communications to counteract blocking events.
Abstract
from arXiv · showhide
Wireless 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 instead 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 paper starts with 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.
1. Introduction
5G integrates multiple networks for diverse sectors and applications rather than introducing only a new radio-access standard, requiring operators to provide diverse network configurations. This paper examines mmWave, combined with densification, massive MIMO, and MEC, through four use cases addressing where, when, and how mmWave will support high-rate and low-latency 5G communications.
- 1. Introduction: 5G’s key novelty is integrating multiple networks for diverse sectors and applications, driving operators to provide a diverse set of networks.Applications include multimedia, VR/AR, M2M/IoT, automotive, and Smart City services [2].
- 1. Introduction: mmWave, network densification, and massive MIMO enable ultra-high-speed access and backhaul, with this paper focusing on 28 GHz and unlicensed 60 GHz.The rationale also applies to future frequencies; 28 GHz is planned for 3GPP NR [5], while 60 GHz is used by IEEE802.11ad/WiGig.
- 1. Introduction: The paper addresses where, when, and how mmWave will be used through four 5G use cases and expected market-entry time frames.It identifies MEC as the mechanism combining ultra-high speed with low latency, while later sections specify deployment scenarios and locations.
- 1. Introduction: A demonstrated millimeter-wave prototype system achieved a 1.25 Gbps peak data rate in a running subway train.The system was demonstrated in February 2017 and was described as the world’s first such prototype in a running subway train.
- 1. Introduction: Early mmWave deployment requires deeper discussion of scenarios, use cases, and enabling technologies despite 28 GHz and 60 GHz potential in South Korea, the US, and Japan.The paper begins with 28 GHz technology for the PyeongChang winter Olympics in 2018 and then moves to 60 GHz technology at Tokyo-Narita airport.
3. 28 GHz Outdoor Backhaul for Fixed Wireless Access and Moving Hotspots
This section presents 28 GHz outdoor mmWave backhaul for fixed wireless access and moving hotspots, including the 5G CHAMPION end-to-end PoC planned for the 2018 PyeongChang Olympics. The deployment targets broadband, ultra-high-rate, mobile, and short-latency services using beamforming, heterogeneous access, virtualized networking, and MEC.
- 28 GHz rationale: The 28 GHz band is favored because licensed spectrum is underutilized, supports cellular links over 500 meters, and preserves multipath and non-line-of-sight capability relative to higher frequencies.A numerology modification can adapt existing technology for cost-effective wireless backhaul and faster feature deployment.
- 5G CHAMPION deployment: The 5G CHAMPION project combines 28 GHz beamforming backhaul, reconfigurable transceivers, distributed or centralized MEC, caching, and virtualized core networking in an operational Olympic PoC.The platform supports fixed hotspots, moving hotspots, high-speed trains, and short-latency applications.
- Target use cases and KPIs: The PoC targets at least 100 Mbps stationary hotspot connectivity, 20 Gbps mmWave links, content delivery at speeds up to 500 km/h, and end-to-end latency below 5 ms.The over-the-air latency target is 2 ms, alongside broadband and inter-system interoperability requirements.
- Moving-hotspot architecture: The moving-hotspot architecture links roadside MHN NodeBs to vehicle-mounted MHN Terminal Equipment, which backhauls traffic over mmWave to onboard Wi-Fi users.The South Korean design uses carrier aggregation, high-performance handover, and polarization-based digital MIMO for broadband service in fast-moving vehicles.
- Link-level performance: 5 Gbps is achievable with 1 GHz bandwidth in the 2x2 MIMO backhaul simulation, which reaches up to 10 bps/Hz average spectral efficiency.The result assumes one mTE for the PyeongChang demonstration.
- Hardware prototypes: A 400-element analogue beamforming array operating at 27.4–31.7 GHz achieves 20.8 dBi maximum broadside gain, with 2.5 dBi and 5 dBi scanning losses at 40° and 60° tilt.The array uses 1-bit tunable phase states and circular polarization.
4. 60 GHz Indoor Access with Mobile Edge Computing
This section presents 60 GHz unlicensed indoor mmWave access combined with MEC for low-latency, high-throughput services in venues such as airports, stations, and shopping malls. A Narita Airport prototype demonstrates ultra-high-speed content delivery, while caching, computation offloading, and multilink access address latency, energy, and blockage constraints.
- Deployment scenarios: 60 GHz unlicensed indoor access targets homes, offices, airports, stations, trains, buses, stadiums, museums, and shopping malls where operators struggle to deploy base stations directly.These venues have limited spatial extent but demand large video transfers and augmented-reality services.
- Mobile Edge Computing: MEC places computing and caching near users through access points, while context-predicted prefetching reduces experienced latency for large downloads despite poor backhaul links.For moving users such as metro passengers, MEC servers along stations or rail lines can coordinate prefetching as users move.
- Applications and offloading: MEC-hosted augmented-reality services provide localized, real-time information that follows users, while computation offloading reduces mobile-device battery burden.These applications require position and viewing-direction awareness, high computational capacity, and low latency.
- System architecture: The system connects low-rate WLAN or LTE users to nearby MEC services over high-rate mmWave links and uses mmWave backhaul to coordinate cloud-enhanced access points.Multiple mmWave links provide simultaneous local-cloud access for distributed users and mitigate intermittent blockage caused by obstacles or similarly angled users.
- Prototype implementation: A WiGig access-point prototype used three 60 GHz beamforming modules for 360° coverage and up to three concurrent links, with 10 Gbps wired AP connections and a 40 Gb/s edge cache.The Narita setup used three APs covering a 10 x 5 m area and nine 4K tablets with IEEE 802.11ad/WiGig dongles.
- Experimental demonstration: 1.7 Gbps maximum throughput enabled a compressed two-hour high-resolution video download in 10 seconds during the nine-day Narita Airport demonstration.The demonstration involved 816 participants, with 99.3% of positive feedback indicating high expectations for practical realization.
5. mmWave Mesh Networks for µ–RAN
In dense urban 5G scenarios, a mmWave mesh network can form a cost-effective µ-RAN by dynamically connecting LTE-gateway and mmWave small-cell backhaul links to follow spatially and temporally varying traffic. Simulations show traffic-aware control reduces energy use, while a WiGig prototype supports flexible backhaul and access.
- 5.1 Dense urban scenario: Dense urban network densification addresses high and dynamic traffic from mobile devices, augmented-reality sensors, and connected cameras, but many small-cell BSs increase CAPEX and OPEX.The mesh backhaul is presented as a solution for relaxing these deployment costs in dense scenarios such as squares, street canyons, and stations.
- 5.1 System architecture: The µ-RAN overlays mmWave small-cell BSs on an LTE macro cell, with the LTE macro BS serving as the mmWave gateway for spatially non-uniform and time-varying traffic.Access and backhaul use three or four sectors, integrating connectivity across the macro and small-cell layers.
- 5.2 Traffic & energy management: The energy-management algorithm first determines small-cell ON/OFF states from demand, then creates power-minimizing backhaul paths, and finally reactivates isolated small cells efficiently.The three-step procedure addresses the difficulty of jointly optimizing small-cell activation and backhaul paths.
- 5.2 Traffic & energy management: The mesh dynamically activates small-cell BSs and forms gateway-to-hotspot backhaul links as traffic shifts between low-demand nighttime and daytime hotspots.At 3 AM, few small-cell BSs are active and most users connect to LTE; around 3 PM, a hotspot appears in the upper-left zone and corresponding backhaul links form.
- 5.2 Traffic & energy management: Network-centric ON reduces energy consumption by about a half through adaptive user association within the µ-RAN.The comparison evaluates Network centric ON, User centric ON, and Always ON under traffic variation throughout a day, with the strongest benefit especially at midnight.
- 5.3 Prototype hardware: The mmWave PoC platform provides point-to-point backhaul coverage up to 400 m and achieves up to 2 Gbps IP throughput at 200 m line of sight while consuming about 20 W.The IEEE 802.11ad/WiGig platform also supports adaptive beam switching and access links; its antenna system provides 41 dBm EIRP and steering capability.
6. mmWave based V2V/V2X for Automated Driving
mmWave-based V2V/V2X targets automated driving by exchanging HD-map and sensor information between vehicles and roadside units under stringent throughput, latency, and range requirements. The proposed architecture uses direct mmWave D2D links, cooperative perception, and candidate licensed frequency bands to support real-time driving decisions.
- Requirements: Enhanced V2V/V2X requires 1 Gbps per link, latency below 10 ms, and a 150–300 m range to exchange raw or lightly processed sensor data for safe automated driving.These requirements motivated 3GPP work on enhanced V2X, or eV2X, in Release 15 and beyond.
- System architecture: mmWave V2V/V2X uses direct D2D links between vehicle-mounted OBUs and RSUs to exchange HD maps while meeting the 1 Gbps and sub-10 ms targets.The architecture is designed for real-time HD-map exchange between surrounding OBUs and RSUs.
- Cooperative perception: OBUs and RSUs fuse received HD maps with local sensor data, apply cooperative perception to widen visibility, and share the resulting map with neighboring units.The fused map supports automated-driving decisions; RSU sensing can additionally provide a native bird’s-eye view that helps detect obstructed objects.
- Cooperative perception: Multiple RSUs mounted on street lamps 6 m high and spaced 40 m apart can continuously monitor roads to detect hidden objects, unequipped vehicles, bicycles, and pedestrians in complex urban environments.This arrangement illustrates cooperative perception created from multiple RSUs along a road.
- Frequency selection: The paper nominates four mmWave V2V/V2X candidates: 31.8–33.4 GHz, 40.5–42.5 GHz, 47.0–50.2 GHz, and 66.0–71.0 GHz.Candidate bands should provide more than 1 GHz bandwidth, use international IMT bands, be licensed to limit interference, and operate independently when PLMNs are unavailable.
7. Concluding Remarks
The conclusion outlines phased mmWave deployment in 5G: 28 GHz backhaul for moving hotspots and 60 GHz access combined with MEC for airport content delivery, followed around 2020 by mmWave mesh networks. It emphasizes that mmWave with MEC addresses both ultra-high speed and low-latency requirements.
- Phased deployment: 28 GHz mmWave will provide backhaul for moving hotspots such as buses, supporting a 2018 PyeongChang Winter Olympics 5G entertainment system and concurrent US use.The deployment is framed as the world’s first 5G entertainment system.
- Phased deployment: 60 GHz mmWave combined with MEC will enable on-demand content downloads for smartphones and tablets at Tokyo-Narita airport in 2018.The service supports Omotenashi for guests attending the 2020 Tokyo Summer Olympics and targets ultra-high speed with low latency.
- Phased deployment: The third deployment phase, around 2020, involves mmWave mesh networks.The supplied passage identifies the phase but does not provide further deployment details.