metis project the 5 g framework

IEEE Communications Magazine • May 201426 0163-6804/14/$25.00 © 2014 IEEE

Afif Osseiran, Olav Que-seth, Hugo Tullberg, Bog-dan Timus, and MikaelFallgren are with Erics-son.

Federico Boccardi is withVodafone. This work wascarried out when he waswith Alcatel-Lucent BellLabs.

Volker Braun is withAlcatel-Lucent Bell Labs.

Katsutoshi Kusume andHidekazu Taoka are withDOCOMO Euro-Labs.

Patrick Marsch andMichal Maternia are withNokia Solutions and Net-works.

Malte Schellmann is withHuawei ERC.

Hans Schotten is with theUniversity of Kaiser-slautern.

Mikko A. Uusitalo is withNokia.

INTRODUCTION

Societal development will lead to changes in theway mobile and wireless communication systemsare used. Essential services such as e-banking, e-learning, and e-health will continue to prolifer-ate and become more mobile. On-demandinformation and entertainment (e.g., in the formof augmented reality) will progressively be deliv-ered over mobile and wireless communicationsystems. These developments will lead to anavalanche of mobile and wireless traffic volume,predicted to increase a thousand-fold over thenext decade [1, 2].

Furthermore, it is generally predicted that

today’s dominating scenarios of human-centriccommunication will, in the future, be comple-mented by a tremendous increase in the num-bers of communicating machines. This so-calledInternet of Things will make our everyday lifemore efficient, comfortable, and safe. There areforecasts of a total of 50 billion connecteddevices by 2020 [3].

The coexistence of human-centric andmachine-type applications will lead to a largediversity of communication characteristics. Someof these applications can be supported by today’smobile broadband networks and their future evo-lution. However, some other applications willimpose additional and very diverse requirementson mobile and wireless communication systemsthat the fifth generation (5G) will have to support:• Far more stringent latency and reliability

requirements are expected to be necessaryto support applications related to health-care, security, logistics, automotive applica-tions, and mission-critical control.

• A wide range of data rates has to be sup-ported, up to multiple gigabits per second,and tens of megabits per second need to beguaranteed with very high availability andreliability.

• Network scalability and flexibility arerequired to support a large number ofdevices with very low complexity andrequirements for very long battery lifetimes.One of the main challenges is to satisfy these

requirements while at the same time addressingthe growing cost pressure. Efficiency and scala-bility are therefore key design criteria, reflectingthe need to respond to the expected explosion oftraffic volume and number of connected devices.

Based on lessons learned in the past, Mobileand Wireless Communications Enablers for theTwenty-Twenty Information Society (METIS)builds on the assumption that a single new radioaccess technology (RAT) will not be able to sat-isfy all these requirements or replace today’s

ABSTRACT

METIS is the EU flagship 5G project withthe objective of laying the foundation for 5G sys-tems and building consensus prior to standard-ization. The METIS overall approach toward 5Gbuilds on the evolution of existing technologiescomplemented by new radio concepts that aredesigned to meet the new and challengingrequirements of use cases today’s radio accessnetworks cannot support. The integration ofthese new radio concepts, such as massiveMIMO, ultra dense networks, moving networks,and device-to-device, ultra reliable, and massivemachine communications, will allow 5G to sup-port the expected increase in mobile data vol-ume while broadening the range of applicationdomains that mobile communications can sup-port beyond 2020. In this article, we describe thescenarios identified for the purpose of drivingthe 5G research direction. Furthermore, we giveinitial directions for the technology components(e.g., link level components, multinode/multi-antenna, multi-RAT, and multi-layer networksand spectrum handling) that will allow the fulfill-ment of the requirements of the identified 5Gscenarios.

5G WIRELESS COMMUNICATIONS SYSTEMS:PROSPECTS AND CHALLENGES

Afif Osseiran, Federico Boccardi, Volker Braun, Katsutoshi Kusume, Patrick Marsch, Michal Maternia,

Olav Queseth, Malte Schellmann, Hans Schotten, Hidekazu Taoka, Hugo Tullberg, Mikko A. Uusitalo,

Bogdan Timus, and Mikael Fallgren

Scenarios for 5G Mobile and Wireless Communications: The Vision of the METIS Project

OSSEIRAN_LAYOUT_Layout 5/7/14 11:17 AM Page 26

IEEE Communications Magazine • May 2014 27

networks. Instead, METIS’s vision is that 5Gnetworks will respond to the expected traffic vol-ume explosion and to the new and diverserequirements mentioned above through a flexi-ble combination of evolved existing technologiesand new radio concepts, as illustrated in Fig. 1.

METIS [4] is an integrated project partlyfunded by the European Commission under theFP7 research framework, and is considered the5G flagship project [5]. The project started inNovember 2012 and has a 30-month duration.METIS is part of a long-term vision roadmap, asshown in Fig. 2. The roadmap can be dividedinto three phases:• The ongoing exploratory phase, which con-

sists of laying the foundation for the 5Gsystem

• The optimization phase, which consists ofsystem optimization and standardization

• The implementation phase, which consistsof pre-commercial trials

The METIS consortium comprises 29 partnersspanning telecommunication manufacturers, net-work operators, the automotive industry, andacademia. Among these are five major globaltelecommunications manufacturers, five globaloperators, and 13 academic partners. METIS’sobjective is to lay the foundation for the 5Gmobile and wireless communications system. Toachieve this objective, METIS is designing a sys-tem concept that delivers the necessary efficien-cy, versatility, and scalability. The project startedby developing relevant scenarios from whichrequirements and key performance indicators(KPIs) were deduced. Research needs on spec-trum, network, multi-link, and radio link issueswere identified, and the corresponding enablingtechnology components are now being devel-oped. These technology components are beingintegrated into a system concept that is evaluat-ed using link- and system-level simulators. Hard-ware testbeds provide proof-of-concept

demonstrations of selected technology compo-nents essential to the system concept. METIShas taken a leading role in exploring the funda-mentals of the 5G mobile and wireless communi-cations system, and it will ensure an early globalconsensus prior to global standardization activi-ties, also involving major external stakeholders.This is achieved, for example, by initiating andaddressing work in relevant fora such as theInternational Telecommunication Union Rado-communication Standards Sector (ITU-R), toprepare for WRC-15 and provide input to WRC-18, as well as in national and regional regulatorybodies. For instance, METIS has been contribut-ing to the ITU-R 2020 vision document [6]. Asimilar approach was taken in the WINNERproject [7], where important technology compo-nents were developed prior to standardization/regulations of Long Term Evolution (LTE) inthe Third Generation Partnership Project(3GPP) and IMT-Advanced in ITU-R.

This article aims at introducing the work inMETIS and contains two main sections. Wedescribe the 5G scenarios and requirements aswell as the methodology used for investigatingthem. Furthermore, we explain METIS’s tech-nology approach toward 5G. In particular, itgives initial directions of the technology compo-nents most likely able to fulfill the requirementsof the 5G scenarios.

METHODOLOGY, REQUIREMENTS,AND SCENARIOS

METHODOLOGYMETIS technology innovation follows a push-pull approach. In a bottom-up process, newradio concepts are developed and optimized tosupport future application needs. In a top-downapproach, relevant use cases as well as serviceand application needs are evaluated in order to

Figure 1. The 5G roadmap: revolution, evolution, and complementary new technologies.

4G3G WiFi

Existing technologies in 2012

5G future

Integrationof access technologies

into one seamless experience

Mobile, reliableD2D communications

10-100 higher typical user rate1000 higher mobile data volume

per area

10 longer battery lifefor low-power M2M

10-100 higher number ofconnected devices

5 reduced E2E latency

Respond to traffic explosion Extend to novel applications

Complementarynew technologies

Evolution

Revolution

Massive MIMO

Ultra-densenetworks

Moving networks

Higher frequences

Ultra-reliablecommunications

Massive machinecommunications

and/or and/or

By using a technolo-

gy agnostic scenario

description, METIS

has avoided tailoring

scenarios to specific

potential technolo-

gies that it wants to

evaluate. Many inter-

esting and challeng-

ing applications can

be identified by fol-

lowing current

trends and projecting

them into 2020.

OSSEIRAN_LAYOUT_Layout 5/7/14 11:17 AM 7

IEEE Communications Magazine • May 201428

derive the requirements that 5G has to meet. In particular, the top-down process is based

on an end-user perspective. Moreover, by usinga technology agnostic scenario description,METIS has avoided tailoring scenarios to specif-ic potential technologies that it wants to evalu-ate. Many interesting and challengingapplications can be identified by following cur-rent trends and projecting them into 2020.METIS has selected a dozen test cases (i.e.,applications or use cases) that are expected tospan the space of possible future uses. Theseexemplary applications have been clustered intofive scenarios, each illustrating a fundamentalchallenge. Some of these challenges are typicalof conventional mobile broadband applications(e.g., very high traffic volume and experienceddata rate); others are essential for applicationsthat are not properly handled in today’s net-works, such as extremely low power consumptionand low latency. Many test cases share many ofthe challenges identified. The fundamental chal-lenges and requirements are described. Wedescribe the five scenarios, and illustrate themwith numeric examples from a few selected testcases. More details of the test cases within eachscenario can be found in [8].

REQUIREMENTSThe identified scenarios and test cases are pre-sented from an end-user (human or machine)perspective. Therefore, the requirements andKPIs are primarily related to the end user. Toevaluate and compare the different technologycomponents addressing the METIS scenarios,some solution-agnostic KPIs [8] are introduced.The KPIs taken as a basis for assessment of theradio link related requirements from the end-user perspective are as follows: traffic volumedensity, experienced end-user throughput, laten-cy, reliability, availability, and retainability.1 Fur-thermore, some KPIs reflecting an energy oreconomic perspective are needed to assess thefinal system solution. We consider energy con-sumption (or efficiency) and cost. Each KPI isgiven a qualitative and mathematical definition[8].

The technical objective of METIS thatreflects the 5G requirements is to develop tech-

nical solutions toward a system concept that sup-ports [9]:• 1000 times higher mobile data volume per

area• 10 to 100 times higher number of connected

devices• 10 to 100 times higher user data rate• 10 times longer battery life for low-power

massive machine communication (MMC)• 5 times reduced end-to-end latency

These requirements shall be fulfilled at simi-lar cost and energy dissipation as today. In orderto derive the corresponding requirements andKPIs, the identified scenarios and applicationsare analyzed. The selected key requirements aresummarized in Table 1. The complete analysiscan be found in [8].

SCENARIOSMETIS has analyzed the above mentioned chal-lenges regarding mobile and wireless infra-structure for beyond 2020 in detail. In order totackle these challenges and target the rightenabling technology components, the followingfive scenarios have been specified:• “Amazingly fast” focuses on providing very

high data rates for future mobile broadbandusers to experience instantaneous connec-tivity without delays.

• “Great service in a crowd” focuses on pro-viding reasonable mobile broadband experi-ences even in crowded areas such asstadiums, concerts, and shopping malls.

• “Best experience follows you” focuses onproviding end users on the move (e.g., incars or trains) with high levels of serviceexperience.

• “Super real-time and reliable connections”focuses on new applications and use caseswith very strict requirements on latency andreliability.

• “Ubiquitous things communicating” focuseson the efficient handling of a very largenumber of devices (including, e.g., machinetype devices and sensors) with widely vary-ing requirements.The scenarios are illustrated in Fig. 3 and

described in more detail below. Further detailscan be found in [8].

Figure 2. The 5G timeline.

WRC ’18

2020

ImplementationExploring new paradigms,fundamentals, system

conceptsOptimization/

standardization

Further developments on fundamentals

WRC ’15WRC ’12

201820152012

1 Retainability is a specialaspect of availability, inwhich a service has beenmade available as long asthe user needs the service[8, Sec.4.2].

The end user will

focus on the experi-

ence, rather than on

the underlying tech-

nology. The flash

behavior will be a

key factor for the

success of cloud ser-

vices and applica-

tions, and an enabler

for the future devel-

opment of new

applications.



Amazingly Fast — This scenario targets theend-user experience of instantaneous connec-tivity, where all used applications will have a“flash” behavior: a single click and theresponse is perceived as instantaneous. Conse-quently, the end user will focus on the experi-ence, rather than on the underlying technology.The flash behavior will be a key factor in thesuccess of cloud services and applications, andan enabler for the future development of newapplications.

An example METIS test case for this sce-nario is the “virtual reality office,” where giga-bytes of data — for instance, high-resolution 3Ddata — are exchanged to enable interactive workamong people in remote locations, proving theexperience “as if one were there.” To supportthat, end users should experience data rates of atleast 1 Gb/s and 5 Gb/s in 95 and 20 percent ofoffice locations, respectively, and during 99 per-cent of the busy period [8].

Great Service in a Crowd — This scenarioaddresses end-user needs for connectivity evenin very crowded places such as stadiums, shop-ping malls, open air festivals, other public eventsthat attract lots of people, or unexpected trafficjams and crowded public transportation.

Today’s mobile communication systems aredesigned so that a user is provided with a rea-sonable mobile broadband experience justwhen there are few users requesting the ser-vice. In the case of large crowds, today’s userstypically suffer from service denials due to net-work overload. However, in the future, it islikely that users will expect at least reasonablygood service even in very crowded places,which poses a significant challenge to futurecommunications system design. As an example,for a METIS test case within this scenario, thetest case “Stadium” foresees a traffic volumeper subscriber of 9 Gbytes/h during busy peri-ods, and an experienced user data rate between0.3 and 20 Mb/s even in a completely filled sta-dium [8].

Best Experience Follows You — This sce-nario strives to bring the same good user expe-rience for an end user on the move as for oneat home or in the office. Users on the moveshall have the impression that “the networkinfrastructure follows them,” in situationswhere they suffer from poor coverage today.High data rate coverage is expected at everylocation of the service area, even in remoterural areas.

High data rate services such as video stream-ing and file downloads in “blind spots” (i.e.,locations with bad coverage) are typical applica-tions for this scenario. The end users should beable to experience a data rate of at least 100Mb/s in the downlink and 20 Mb/s in the uplink,while maintaining end-to-end latencies below100 ms. Availability must be as high as 95 per-cent in blind spots [8].

The technical challenge is to provide robustand reliable connectivity solutions as well as theability to efficiently manage mobility with lowbattery consumption of end-user terminals andat low cost.

Super Real-Time and Reliable Connec-tions — The reliability and latency in today’scommunication systems have been designedwith the human user in mind. For future wire-less systems, it is envisioned to have new appli-cations based on machine-to-machine (M2M)communication with real-time constraints,enabling new functionalities for traffic safetyand traffic efficiency, or mission-critical con-trol for industrial applications. These newapplications will require much higher reliabili-ty and lower latency than today’s communica-tion systems.

The METIS test case “Traffic efficiency andsafety” is a typical application for a super real-time and reliable connections scenario wheretraffic accidents are avoided by cooperativeintelligent traffic systems that require timelyand reliable exchange of information with lessthan 5 ms end-to-end (E2E) latency. “Telepro-tection in smart grid networks” is considered asanother relevant application demanding reliableinformation transfer between power grid sub-stations within the range of a few milliseconds.Smart grid networks may require real-timemonitoring and alerting functionalities, andimmediate response to altered system condi-tions. The expected payload sizes are rathermoderate, say up to about 1500 bytes, while themessages shall be transferred with 99.999 per-cent reliability with about 8 ms delay on theapplication layer [8].

Key technical challenges lie in reducing theE2E latency while providing high accessibilityand reliability of the communication services.

Ubiquitous Things Communicating — Thisscenario addresses the communication needs ofubiquitous machine-type devices, ranging fromlow-complexity devices (e.g., sensors and actua-tors) to more advanced devices (e.g., medicaldevices). The resulting requirements vary wide-ly, for example, in terms of payload size, fre-quency of transmission, complexity (cost),

Table 1. A selection of the key requirements and respective applicationexamples.

Requirements Desired value Application example

Data rate 1 to 10 Gb/s Virtual reality office

Data volume

9 Gbytes/h in busy period500 Gbytes/mo/sub-scriber

StadiumDense urban information society

Latency Less than 5 ms Traffic efficiency and safety

Battery life One decade Massive deployment of sensorsand actuators

Connecteddevices

300,000 devices perAP

Massive deployment of sensorsand actuators

Reliability 99.999%Teleprotection in smart grid net-workTraffic efficiency and safety



energy consumption, transmission power, andlatency, and cannot be fully met by today’s cel-lular networks.

“Massive deployment of sensors and actua-tors” is a typical application where small sensorsand actuators are mounted to stationary or mov-able objects and enable a wide range of applica-tions connected to monitoring, alerting oractuating. The requirements will be to provideconnectivity for 300,000 devices within one cell,enable long battery life (on the order of adecade) and low cost device implementations, soas to support the billions of connected devicesexpected by 2020 [8].

The technical challenge is to integrate thecommunication of ubiquitous things in mobilenetworks and to manage the overhead createdby the high number of devices.

We note that some METIS test cases cannotbe mapped to a single scenario, but rather repre-sent a combination of different scenarios andtheir underlying challenges. For instance, thetest case “dense urban information society” doesnot require the extreme data rates of the “virtualreality office” case or the latency connected to“traffic efficiency and safety,” but foresees bothhumans and machines enjoying reasonably highdata rates at reasonably low latencies, bothindoors and outdoors, and also when devices aremoving jointly in crowds (e.g., on a pedestriansidewalk). The key difficulty here is thus toaddress the product of multiple requirementsunder constrained network deployment costs. Inparticular, the requirement will be to enable in95 percent of locations and time an experienceddata rate of 300 Mb/s and 60 Mb/s in the down-link and uplink, respectively, and a data rate of10 Mb/s between, say, sensors and devices. Ulti-mately, the network is required to provide theabove date rate while sustaining an average traf-fic volume of 500 Gbytes per device and permonth. This corresponds to about 1000 timestoday’s average monthly traffic volume per sub-scriber [8].

THE METIS TECHNOLOGYAPPROACH TOWARD 5G

The challenges described earlier will beaddressed by a combination of different solu-tions. Each of these solutions may include sever-al novel technological building blocks andtechnological enablers.

THE METIS HORIZONTAL TOPICSMETIS uses so-called horizontal topics (HTs) tobuild the overall system concept. An HT inte-grates a subset of the technology components toprovide the most promising solution to one ormore test cases.

The HT-specific solutions will be integratedinto the overall METIS system concept. Poten-tial overlaps between HTs, trade-offs, and inter-dependencies between technology componentswill be identified and analyzed with respect totheir impact on overall system performance. Theperformance of the proposed concept will beevaluated according to the research objectivesand KPIs. The research work will be directed bythe concept development to ensure consistentintegration of the developed technology compo-nents. The METIS HTs are described below.Additional HT(s) can be added to captureemerging market, societal, technical, and eco-nomical trends.

Direct device-to-device (D2D) communicationrefers to direct communication between devices,without user-plane traffic going through any net-work infrastructure. Under normal conditionsthe network controls the radio resource usage ofthe direct links to minimize the resulting inter-ference. The goals are to increase coverage,offload backhaul, provide fallback connectivity,and increase spectrum utilization and capacityper area.

Massive machine communication (MMC)provides up- and down-scalable connectivitysolutions for tens of billions of network-enabled

Figure 3. The 5G scenarios defined in METIS.

1 Gb/s

5 Gb/s

Amazingly fast

Great service in a crowd

OperatorA

Operator B

Local contentprovider

Cloud serviceprovider A

Cloud serviceprovider B

Operator C

Cloud serviceprovider

Ubiquitous things communicating

Wired andfire sensors

Super real-time and reliable connections

People communicatingand exchanging content

Wind andhumidity sensors

Best experience follows you

Data storage

Emerging servicesReal time services

100 Mb/s

10 Mb/s

1 Mb/s

Data access

Ultra lowlatency

Ultra highreliability

Ultra lowlatency


Ultra lowlatency




devices, which is vital for future mobile andwireless communication systems. Machine-relat-ed communications have a wide range of charac-teristics and requirements (e.g., data rate,latency, and cost) that often differ substantiallyfrom those of human-centric communication.

Moving networks (MNs) enhance and extendcoverage for potentially large populations thatare part of jointly moving communicationdevices. An MN node or a group of such nodescan form an MN that communicates with itsenvironment, that is, other nodes, fixed ormobile, inside or even outside the moving entity.

Ultra-dense networks (UDNs) address thehigh traffic demands via infrastructure densifica-tion. The goals are to increase capacity, increaseenergy efficiency of radio links, and enable bet-ter exploitation of spectrum. UDNs are ordersof magnitude denser than today, assuming, forinstance, several access nodes per room indoorsand an access node on each lamppost outdoors,which of course raises severe interference andmobility challenges, and increased pressure oncost per access node.

Ultra-reliable communication (URC) willenable high degrees of availability. METIS aimsto provide scalable and cost-efficient solutionsfor networks supporting services with extremerequirements on availability and reliability.

Architecture (Arch) provides a consistentarchitectural framework integrating differentcentralized and decentralized approaches.METIS will research and introduce a novelarchitectural concept that can take advantage ofthe developed technology components in a scal-able way.

TECHNOLOGY COMPONENTSIn order to develop the connectivity solutionsand mobile communications system for societybeyond 2020 with its broad range of service andapplication requirements, METIS develops thefollowing technology components where signifi-cant progress beyond the state of the art isrequired: radio links, multi-node/multi-antennatechnologies, multi-layer and multi-RAT net-works, and spectrum usage. These technologycomponents are briefly described below.

Radio Links — To efficiently support the vastrange of identified use cases and scenarios, an airinterface providing a “one-size-fits-all” solutionno longer seems to be the favorable choice.Instead, the air interface for the future mobileradio system should become more flexible, pro-viding different solutions for particular use casesand applications under a common umbrellaframework [10]. For a UDN, where the system isexpected to support a large range of carrier fre-quencies, flexibility is brought to the system by anair interface with a scalable frame structure, pro-viding a low-cost solution for adapting the systemto the signal conditions specific to the utilizedbands. The efficient support of machine-typecommunication in parallel to human-centric com-munication is enabled by an optimized signalingstructure, reducing the signaling overhead forMMC. Requirements of car-to-car applicationsare addressed by solutions aiming to improvereliability and quality of transmission at high

vehicular speeds, also embracing novel approach-es to channel estimation and prediction.

For the physical layer, a particular challengeis the efficient support of a broad range of datarates going from low-rate sensor applications upto ultra-high-rate multimedia services. For thispurpose, waveforms, coding and modulationschemes, and suitable transceiver structures areinvestigated. Faster than Nyquist (FTN) trans-mission is studied as a technique for increasingthe data rate at the cost of higher complexity ofthe receiver design. Filtered and filter-bank-based multi-carrier schemes are consideredpotential new waveform candidates for the futuremobile radio system because they allow for effi-cient use of fragmented spectrum, and facilitatespectrum sharing with other services and appli-cations. In the context of advanced transceiverdesign, full duplex transmission seems to be apromising technology, allowing a node to simul-taneously transmit and receive a signal, thusincreasing the spectral efficiency of the link.

The new scenarios will also yield the intro-duction of new classes of devices and services,which should be efficiently supported by appro-priate multiple access (MA), medium accesscontrol (MAC), and radio resource management(RRM) techniques. Non- and quasi-orthogonalMA techniques are investigated, where the num-ber of users is no longer limited by the set oforthogonal resources, thus allowing the spectrumto be overloaded. In the area of MAC, researchcovers contention-based schemes for efficientaccess to a massive number of machine-typedevices and distributed techniques for the syn-chronization of a set of nodes if no or only limit-ed access to the network is available.Deadline-driven hybrid automatic repeat request(HARQ) concepts address the needs of URC, asthey guarantee to deliver a packet within a speci-fied deadline.

Detailed descriptions of all radio linkresearch topics can be found in METIS deliver-able D2.2 [14], and results from their assessmentin deliverable D2.3 [15].

Multi-Node/Multi-Antenna Transmission —In METIS, improvements on multi-node/multi-antenna technologies are addressed to achievethe performance and capability targets of 5Gwireless systems [11], by looking at both evolu-tions of 4G technologies and disruptive changesat both the node and architectural levels (Fig. 4).

Massive multiple-input multiple-output(MIMO) is studied in order to deliver very highdata rates and spectral efficiency, as well asenhanced link reliability, coverage, and/or energyefficiency. Part of the work is dedicated toassessing the impact of real-world challenges,such as channel estimation and pilot design,antenna calibration, link adaptation, and propa-gation effects. Another part of the work is dedi-cated to studying the effect of new types of arraydeployments. An additional part of the work isfurther exploring the theoretical limits of mas-sive MIMO [11]. Finally, the use of massiveMIMO solutions in millimeter-wave bands isalso considered.

Advanced inter-node coordination is expect-ed to achieve significant increases in spectrum

In METIS, improve-

ments on multi-

node/multi-antenna

technologies are

addressed to achieve

the performance and

capability targets of

5G wireless systems,

by looking at both

evolutions of 4G

technologies and

disruptive changes at

both the node and

architectural levels.



efficiency and user throughput, and improve-ments for users with unfavorable radio condi-tions. METIS is currently exploring threedifferent broad research directions related tointer-node coordination. The first one is furtherimprovement of classical coordination tech-niques. Different from previous studies, coordi-nation is designed as a core characteristic of thenetwork, rather than as an add-on feature (e.g.,LTE Rel. 10). The second broad research direc-tion explored within METIS is interferencealignment. The third research direction is coor-dination with enhanced network and UE capa-bilities. For example, METIS is investigating thepossibility for 5G UEs to take a more active rolein the network (e.g., selecting the set of servingbase stations, performing advanced interferencerejection, or exploiting local cooperation).

Network densification, reliability, and supportof moving networks may make relaying and mul-tihop communications one of the central ele-ments in the wireless architecture (in contrast toexisting wireless networks where multihop com-munications have been considered as an addi-tional feature). METIS’s research approachaddresses network densification through the useof infrastructure-deployed relays and techniquesfor wireless backhauling. Specifically, wirelessnetwork coding, buffer-aided relaying, and jointprocessing of interfering flows are considered byMETIS promising research directions to makewireless relaying a viable option for efficient in-band backhauling.

Heterogeneous Multi-RAT and Multi-LayerNetworks — In 5G wireless systems, we will seea co-existence of legacy RATs and new accesstechnologies, as well as very dense multi-layernetworks consisting of cells of very differentsizes. Both aspects raise novel challenges in thefield of interference and mobility management,which call for new approaches in how cellularsystems are handled in general.

For instance, the very dense deploymentsexpected beyond 2020 will lead to fewer usersper cell, and traffic will therefore be more bursty,which suggests the usage of time-division duplex(TDD) for more efficient usage of radioresources. In conjunction with possible wide-

spread usage of direct D2D and vehicle-to-X(V2X) communication, the interference constel-lations will be different than observed today. Inthis respect, METIS proposes schemes to identifyand predict interference. Furthermore, METIS isinvestigating a diverse portfolio from highly cen-tralized to distributed or fully decentralizedRRM concepts, and assessing this regarding theachieved trade-off between system performance,minimized infrastructure, signaling overhead, aswell as with respect to scalability. Of course,highly densified networks and a more prominentrole of D2D communication lead to new mobilitymanagement challenges. METIS is tackling thesechallenges by developing novel schemes tailoredspecifically for moving cells, or low-power andlow-cost machine-type devices. Here, a widerange of approaches is considered, including userautonomous, network assisted, or fully networkdriven service connectivity management.

To address both interference and mobilitymanagement aspects in 5G in one holistic frame-work, METIS is also considering a completeredesign of control and user plane functionality,and novel cell concepts, for example, phantomor virtual cells that are fully or partially transpar-ent to the device.

One clear differentiator between a 5G systemand earlier generations will be that one willmove toward proactive management of demand,mobility, and interference instead of simplyreacting to instantaneous channel, demand, andnetwork conditions. This will be made possibleby an extensive prediction and exploitation ofdevice and application context.

Clearly, novel multi-RAT and multi-layersolutions require novel infrastructure enablerssuch as new network management interfaces,which are also investigated in METIS as themost promising technology components arebecoming clear. Furthermore, the partners arealso investigating the integration of nomadiccells (e.g., access nodes mounted on vehicles)with the static infrastructure.

Ultimately, the aim of the multi-RAT andmulti-layer activities is to find answers to funda-mental questions regarding interference andmobility management in 5G, such as to whatextent centralized approaches will be needed

Figure 4. Multi-node/multi-antenna transmission research in METIS.

Massive antennaNetwork coding

Advancedinter-node

coordination

Massive machinecommunication

Multihopcommunications

Device-to-devicecommunication

P1 P2

P2 ⊕ P2



and what implications on the network infra-structure these bring. First investigation results,such as assessing the gains of context awarenessand enablers for cost- and energy-efficient net-work operations, can be found in [13].

Spectrum Usage — METIS has been investi-gating ways to enable and secure sufficient accessto spectrum for wireless communication systemsbeyond 2020 by developing innovative spectrum-sharing concepts. This should lead to substantialimprovements in overall spectrum utilization andresult in significantly increased spectrum usageefficiency from a spectrum-oriented as well as aneconomic point of view.

In the beginning, the focus has been on fre-quency-band analysis in order to identify newspectrum resources and understand their charac-teristics, and on a scenario analysis of futurewireless communication systems in order tounderstand spectrum requirements for systemsbeyond 2020. Frequency band analysis has beenlooking for opportunities even up to 275 GHz.

In a second step, innovative concepts andenablers for shared spectrum usage and flexiblespectrum management have been initially devel-oped. Here, some examples of novelty includeidentification of required enablers for ultra-dense network deployments operating at highfrequencies as well as spectrum management forautonomous and network-assisted D2D commu-nication supporting high mobility.

The frequency range 380–5925 MHz is cur-rently used by many different services. Possibili-ties to accommodate additional IMT bands arebeing considered in the scope of the ITU-RWRC-15 preparation process in detail. Thus, noin-depth investigation of this frequency range isnecessary within the METIS project. It shouldbe noted that any radio access system aiming atproviding coverage in an extended area must usethis frequency range for technical and economicreasons. Therefore, most of the METIS scenar-ios and test cases will need to use at least oneRAT in this frequency range. Additionally, inorder to fulfill the requirements of the describedtest cases, the communicating devices must alsobe equipped with RATs that can access higherfrequency ranges with large bandwidths [12].The highest priority for the next work for fre-quencies above 6 GHz is on frequencies between40 and 90 GHz.

Initial analysis [12] indicates that not only aremore spectrum and more efficient spectrumusage concepts required, but also spectrum engi-neering with respect to guaranteeing coexistence,compatibility, and coverage due to the broaderrange of application requirements.

CONCLUSIONSIn this article, the 5G mobile communicationsscenarios were identified. These scenarios reflectthe foreseen challenges such as high data rate,accessibility, mobility, massive amounts ofdevices, low latency, and reliability. Further-more, the scenarios and test cases were present-ed from an end-user (human or machine)perspective, and the requirements and solution-agnostic KPIs were introduced.

To target each scenario, research is carriedout on technology components such as link-levelcomponents, multi-node/multi-antenna, multi-RAT and multi-layer networks, and spectrumhandling. The METIS overall approach to 5G isto build on the evolution of existing technologiescomplemented by the integration of complemen-tary concepts and, when needed, new radioaccess technologies.

The integration of new radio concepts such asmassive MIMO, ultra-dense networks, movingnetworks, direct device-to-device communica-tion, ultra-reliable communication, massivemachine communication, and others, and theexploitation of new spectrum bands will allowsupport of the expected dramatic increase in themobile data volume while broadening the rangeof application domains that mobile communica-tions can support beyond 2020.

ACKNOWLEDGMENTSPart of this work has been performed in theframework of the FP7 project ICT-317669METIS, which is partly funded by the EuropeanUnion. The authors would like to acknowledgethe contributions of their colleagues in METIS.

REFERENCES[1] Cisco, “Global Mobile Data Traffic Forecast Update,”

2010–2015 White Paper, Feb. 2011.[2] Nokia Siemens Networks 2011, “2020: Beyond 4G

Radio Evolution for the Gigabit Experience,” WhitePaper, Feb. 2011, http://nsn.com/sites/default/files/docu-ment/nokia_siemens_networks_beyond_4g_white_paper_online_20082011_0.pdf.

Figure 5. Heterogeneous multi-RAT and multi-layer networks research scope in METIS.

?

1

Device to deviceMoving networks

Interferencemanagement

Smart mobilitymanagementSmart radio resource

management

Management interfacesNovel cell concepts

Context awareness

The integration of

the new radio con-

cepts and the

exploitation of new

spectrum bands will

allow support of the

expected dramatic

increase in the

mobile data volume

while broadening

the range of applica-

tion domains that

mobile communica-

tions can support

beyond 2020.


http://nsn.com/sites/default/files/document/nokia_siemens_networks_beyond_4g_white_paper_online_20082011_0.pdf


[3] Ericsson, “More than 50 Billion Connected Devices,”White Paper, Feb. 2011, http://www.ericsson.com/res/docs/whitepapers/wp-50-billions.pdf.

[4] METIS, Mobile and Wireless Communications Enablers forthe Twenty-Twenty Information Society, EU 7th FrameworkProgramme project, http://www.metis2020.com.

[5] EU Press Release, “€50 Million EU Research Grants in2013 to Develop ‘5G’ Technology,” Feb. 2013,http://europa.eu/rapid/press-release_IP-13-159_en.htm.

[6] ITU-R M.[IMT.VISION], “IMT Vision — Framework andOverall Objectives of the Future Development of IMTfor 2020 and Beyond,” ITU Working Document5D/TEMP/224-E, July 2013

[7] WINNER Project IST 2004-507581, WINNER II ProjectIST-4-027756 and WINNER+ Project CELTIC CP5-026,http://projects.celtic-initiative.org/winner+/.

[8] ICT-317669 METIS Project, “Scenarios, Requirementsand KPIs for 5G Mobile and Wireless System,” Del.D1.1, May 2013, https://www.metis2020.com/docu-ments/deliverables/.

[9] A. Osseiran et al., “The Foundation of the Mobile andWireless Communications System for 2020 and BeyondChallenges, Enablers and Technology Solutions,” VTC-Spring 2013, June 2–5, 2013.

[10] ICT-317669 METIS Project, “Requirements and GeneralDesign Principles for New Air Interface,” Del. D2.1, Aug.2013, https://www.metis2020.com/documents/deliver-ables/.

[11] ICT-317669 METIS project, “Positioning of Multi-Node/Multi-Antenna Transmission Technologies,” Del.D3.1, July 2013, https://www.metis2020.com/docu-ments/deliverables/.

[12] ICT-317669 METIS project, “Intermediate Descriptionof the Spectrum Needs and Usage Principles,” Del.D5.1, Aug. 2013, https://www.metis2020.com/docu-ments/deliverables/.

[13] ICT-31766 METIS project, “Summary on PreliminaryTrade-Off Investigations and First Set of Potential Net-work-Level Solutions,” Del. D4.1, Sept. 2013,https://www.metis2020.com/documents/deliverables/.

[14] ICT-317669 METIS project, “Novel Radio Link Conceptsand State of the Art Analysis,” Del. D2.2, Oct. 2013,https://www.metis2020.com/documents/deliverables/.

[15] ICT-317669 METIS project, “Components of A New AirInterface — Building Blocks and Performance,” Del.D2.3, Apr. 2014, https://www.metis2020.com/docu-ments/deliverables/.

BIOGRAPHIESAFIF OSSEIRAN [SM] is director of radio communicationswithin the Industry Area Telecom at the Ericsson CTOoffice. He holds a doctorate degree from the Royal Insti-tute of Technology (KTH), Stockholm, Sweden. Since 1999he has been with Ericsson, Sweden. From April 2008 toJune 2010, he was the Technical Manager of the EurekaCeltic project WINNER+. From November 2012 to April2014, he managed METIS, the EU project on 5G. He haspublished over 50 technical papers in international journalsand conferences. He has co-authored two books on IMT-Advanced with Wiley.

FEDERICO BOCCARDI is a principal engineer in the VodafoneGroup. He received his M.Sc and Ph.D. degrees in telecom-munication engineering from the University of Padova,Italy, in 2002 and 2007, respectively, and his postgraduatediploma in strategy and innovation from the Oxford SaïdBusiness School in 2014. Before joining Vodafone, he waswith Bell Labs (Alcatel-Lucent) UK from 2006 to 2010 andwith Bell Labs Germany from 2010 to 2013. He participat-ed and held leadership positions in different EU collabora-tive projects and in the 3GPP standardization activity forLTE and LTE-Advanced. He holds more than 100 issued orpending patents, peer reviewed iternational researchpapers, and 3GPP contributions. His interests fall in theintersection between technology innovation and strategy,and he is currently working on different aspects related to5G.

VOLKER BRAUN (Ph.D.) is with Alcatel-Lucent Bell Labs (for-merly Alcatel Research & Innovation), Stuttgart, Germany,since 1999. He led the development of the base stationsoftware for the HSPA fast radio resource management,and defined and integrated an LTE pre-standard prototypesystem used for early customer mobility trials. He furtherpioneered the concept of outdoor infrastructure small cells.Currently he is working on various 5G research aspects.

KATSUTOSHI KUSUME received his M.Sc. and Dr.-Ing. degreesfrom the Munich University of Technology (TUM) in 2001and 2010, respectively. In 2002, he joined DOCOMO Euro-Labs and is currently manager of the Wireless ResearchGroup. He received the best paper award at IEEE GLOBE-COM in 2009. His research interests include multiple anten-na systems, multicarrier transmissions, iterative techniques,ad hoc networking, and device-to-device communications.

PATRICK MARSCH received his Dipl.-Ing. and Dr.-Ing. degreesfrom Technische Universität Dresden, Germany, in 2004and 2010, respectively. He was the Technical Project Coor-dinator of the project EASY-C, where the world’s largestresearch testbeds for LTE-Advanced were established. Afterheading a research group at TU Dresden, he is now man-aging a research department within Nokia Solutions andNetworks in Wrocław, Poland. He has (co-)authored 50+journal and conference papers, received three best paperawards, been editor of or contributor to several books, andhas been awarded the Philipp Reis Prize for pioneeringresearch in the field of coordinated multipoint (CoMP). Hehas co-organized multiple IEEE workshops and served onvarious technical program committees, for instance, servingas Symposium Co-Chair of IEEE VTC-Spring 2013.

MICHAL MATERNIA received his Master’s in optical telecom-munications from Wroclaw Technical University. He startedhis career at NSN in 2006, where he has been involved inmultiple research projects focused on system-level aspectsof 3G, 4G, and beyond 4G. His research has ranged frommobility aspects through deployment research and interfer-ence management. Since 2013 he has been leading theMulti-RAT/Multi-Layer work package in the 5G projectMETIS.

OLAV QUESETH received his M.Sc. in computer engineeringfrom Chalmers University, Sweden, in 1995 and a Ph.D.degree on radio communications networks from KTH in2005. In 2007 he joined Ericsson and currently holds asenior researcher position. He has worked in 3GPP stan-dardization and regulatory fora, mainly on radio prefor-mance and spectrum issues. Since 2012 he has beenleading the dissemination work in METIS. He became theMETIS Project Coordinator in April 2014.

MALTE SCHELLMANN received his Dipl.-Ing. (M.S.) degree inelectrical engineering from Technische Universität Münchenin 2003 and his Dr.-Ing. (Ph.D.) degree from TechnischeUniversität Berlin in 2009. While working at FraunhoferHeinrich Hertz Institute, Berlin (2004–2009), he contributedto the European research projects WINNER, WINNER II, andWINNER+. Since 2009 he has been a senior research engi-neer at Huawei European Research Center (ERC) in Munich,focusing on radio access technology research for 5G. InMETIS, he is leading the research on radio link concepts.

HANS SCHOTTEN is a full professor and head of the Institutefor Wireless Communications and Navigation at the Univer-sity of Kaiserslautern, and scientific director and memberof the Management Board of the German Research Centrefor Artificial Intelligence (DFKI GmbH). In 1997, he receiveda Ph.D. in electrical engineering from Aachen University ofTechnology RWTH, Germany. He held positions as seniorresearcher, project manager, and head of research groupsat Aachen University of Technology, Ericsson CorporateResearch, and Qualcomm Corporate R&D. At Qualcomm hehas also been director for Technical Standards and coordi-nator of Qualcomm's activities in European research pro-grams. He is the author of more than 160 publications. Hismain interests are mobile communications, algebraic cod-ing, and industrial communication solutions.

HIDEKAZU TAOKA received his B.S. and M.S. degrees from theDepartment of Physics of Kyoto University, Japan, in 1998and 2000, and received his Dr. Eng. degree from TohokuUniversity, Sendai, Japan, in 2009. In 2000, he joined NTTDOCOMO, Inc. Since joining NTT DOCOMO, he has beenengaged in the research and development of wirelessaccess technologies, including multiple-antenna transmis-sion techniques, relaying and network coding techniques,and future radio access techniques for next generationmobile communication systems. From 2006 to 2010, hewas also engaged in standardization in 3GPP RAN1 as adelegate in multiple antenna technologies. From 2010 to2013, he worked at DOCOMO Communications Laborato-ries Europe GmbH, Munich, Germany, as an expatriatefrom NTT DOCOMO, Inc. From 2012 to 2013, he served as


http://www.metis2020.com

http://europa.eu/rapid/press-release_IP-13-159_en.htm

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http://www.ericsson.com/res/docs/whitepapers/wp-50-billions.pdf

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a work package leader to an EU funded research projecton 5G radio access, METIS, to define scenarios and require-ments for future radio access. He is now manager of theGeneral Affairs Department of NTT DOCOMO, Inc.

HUGO TULLBERG is the Technical Coordinator of the EU FP7project METIS. He received his M.Sc. degree in electricalengineering from Lund University, and his Ph.D. degree inelectrical engineering, communication theory, and systems,from the University of California at San Diego (UCSD). Hehas held positions as project manager and research man-ager in various areas related wireless communication. He iscurrently a senior researcher at Ericsson Research, where heworks with 5G communication systems. His research inter-ests include communication and information theory, infer-ence systems, cognitive radio, and ad hoc networking.

MIKKO A. UUSITALO [SM] is a principal researcher at NokiaResearch Center Finland in the area of radio access sys-tems. He is also a Fellow of WWRF. He obtained his M.Sc.(engineering) and Dr.Tech. from Helsinki University of Tech-nology in 1993 and 1997, and hisB.Sc. (economics) from

Helsinki School of Economics in 2003. Before his currentrole, he was head of International Cooperation at NokiaResearch. He has over 30 peer reviewed publications andaround 80 pending or granted patents.

BOGDAN TIMUS [M] is a senior researcher at EricssonResearch, Stockholm, Sweden, in the area of wirelessaccess networks. He received an M.Sc. degree fromChalmers University of Technology in 1997 and a Ph.D.degree from KTH in 2009. He has been with EricssonResearch since 1997. He has been Secretary of the IEEEComSoc/VTC Chapter in Sweden. His research interestsinclude evolution of radio communication networks andtechno-economic analysis of deployment strategies.

MIKAEL FALLGREN received an M.Sc. degree in engineeringphysics and a Ph.D. degree in applied and computationalmathematics from KTH in 2006 and 2011, respectively. Hehas been an experienced researcher at Ericsson Research,Stockholm, Sweden, in the area of wireless access net-works since 2011. He has led the Scenarios, Requirementsand KPIs task of the EU FP7 project METIS since 2013.
