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FANTASTIC-5G: Novel, flexible air interface for enabling efficient multi-service coexistence for 5G below 6GHzFrank Schaich with support from the whole consortiumJanuary 28. 2016

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Agenda

• Introduction- Main ambitions of 5G and key challenge- Why a multi-service air interface instead of dedicated solutions?- Use case selection

• The Project

• Some exemplary technologies- Waveform design- Enablers for massive access- Flexible frame design and radio resource management

• Extension of the FANTASTIC-5G air interface to specialized scenarios andextreme cases

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IntroductionMain ambitions of 5G and key challenge

1. Finding a response to the strong growth of requested data rates both per connection and overall (evolutionary effect)

2. Enhancing the business model of operators by widening the pool of services (revolutionarytarget)

• Key challenge: extremely high degree of heterogeneity in terms of

- Offered services (MBB, MMC, MCC, BMS, V2X) and the respective requirements

- Supported device classes (from low-end sensor to high-end tablet)

- Deployment types (macro layer, small cells)

- Environments (low-density areas to ultra-dense urban)

- Mobility levels (from static to high-speed transport)

FANTASTIC-5G targets to develop a flexible and scalable multi-service air interface (ambition 2) with ubiquitous coverage and high capacity where and when needed (ambition1)

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IntroductionWhy a multi-service air interface instead of dedicated solutions?

• Less carriers to be active in parallel

• More efficient use of the active carrier(s) – use case multiplexing, resource sharing

• Economy of scale – shared functions

• Forward compatibility assured – future use cases might deviate from the settings of specialisedair interfaces.

• Specific devices (e.g. smart phones, cars) may comprise different use cases concurrentlybenefiting from a single harmonized air interface (e.g. eMBB for streaming, MMC for instant messaging, MCC for mobile gaming)

• Increased flexibility

It is easier to run a multi-service air interface in a specialized configuration than to assure broad applicability with specialized solutions (4G and the need of 5G as example)

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• We base our investigations on the following set of use cases (following NGMN recommendations):

- 50 Mbps everywhere- High speed train- Sensor networks- Tactile Internet- Automatic traffic control/driving- Broadcast like services: Local, Regional, National- Dense Urban Society (below 6 GHz)

• The last item is a modified version taking the project considerations into account (to stay below 6 GHz)

Our aim has been to have a representative set of 5G use cases, while keeping the number (and thus the overhead) at a reasonable level.

IntroductionUse case selection

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The Project

• Flexible Air iNTerfAce for Scalable service delivery wiThin wIreless Communication networks of the 5th Generation

• Start: July 1. 2015

• Duration: 2 years

• Part of the overall 5G PPP framework

The participation of multiple vendors (Nokia, Alcatel-Lucent, Huawei), equipment manufacturers (Intel, Samsung, Sequans) and operators (Orange, Telecom Italia) highlights

the ambition and capability of having an impact to standardization

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Some exemplary technologies

• In the following we provide some details on specific components being investigated in the project

- Waveform design- Enablers for massive access- flexible frame design and radio resource management

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Waveform design (candidates under study)

WF Features Pros Cons Targeted service

UF-OFDM / F-OFDM

OFDM compatible, Low OOBE for sub-band

sub-band wise configurability,async. FDMA access support

slightly more prone to delay-spread channels

Multi-service

ZT-OFDM Good coexist. capabilities thanks to low OOBE

Coexist. with OFDM,zero-tail adjustable

Overhead ~ zero tail MTC

FC-OFDM Multiplexing of diff. WFsin the transmission band

Coexistence of diff. WFs in the same band

Constraints on filterlength

All - each service may use its own WF

FBMC-OQAM min. OOBE (steepest decay), max. SE, real-field orthogonality

sub-band wise configurability,robustness to t/f distortions, full async. access support

Not fully OFDM comp.,Long filter tails incr.delay for short bursts

Multi-service

FS-FBMC FBMC-OQAM with large FFT for mod. /demod.,simple parametrization

Like FBMC-OQAM + supports large delay spreads & en-larged support of time async.

Like FBMC-OQAM Multi-service

FBMC-QAM FBMC with QAM supportOFDM compatible

sub-band wise configurability,async. FDMA access support

t/f localization is compromised

Multi-service

P-OFDM pulse shaping as add. DoF OFDM compatible, low OOBE, CP-like overhead

sub-band wise configurability,robustness to t/f distortions, full async. access support

complexity slightly higher than OFDM

Multi-service

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OOBE: Out of band emissions WF: waveformDoF: degree of freedom CP: cyclic prefixSE: spectral efficiency

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Enablers for massive access

• A key characteristic of massive machine access is sporadic traffic from a very high number ofsources.

• Scheduled access procedures (4G) are not very suitable for this (overhead, energy consumption)

• Simplified but robust access mechanisms need to be developed. Two options are underinvestigation:

- Wake-up and transmit (1-stage procedures)- Wake-up, raise hand and transmit (2-stage procedures)

• Two aspects requiring deeper investigations:

- Protocol design- User identification

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Enablers for massive access – protocol designOne-stage vs. two stage protocols

• Faster if successful

• Significantly less DL feedback

• High collision probability reduces throughput

• Coexistence with scheduled traffic difficult to handle

• Envisaged solution for very small packets and low traffic load

• Additional delay

• Depending on configuration certain amount of DL feedback required

• Reduced collision probability through service request over-provisioning increases throughput

• Envisaged solution for bigger packets and higher traffic load

Significant reduction ofoverhead compared to LTE

UE

eNodeB

Info regarding resource assignment

ACK

Data

Service request

UE

eNodeBACK

DataPreamble

Novel preamble design withpotentially more efficientusage of resources

Both variants require a pool of identifiers (preamble, service request)

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Enablers for massive access – protocol designOne-stage vs. two stage protocols

1-step protocol is an attractive solution in low-mid load situation

Protocols with higher flexibility like the 2-stage protocols are better suited in high load situations. They : a) allow a higher arrival rate and b) achieve a higher cell capacity

Both variants benefit from multi-user detection (work in progress)

1-stage protocol is able to upload packets quicker than 2-stage protocols as long the arrival rate is below threshold

2-stage pooled protocol is able to upload packets much quicker than the 2-stage tagged approach

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Enablers for massive access – user identification

• Starting point: Preamble design of 4G (PRACH)

- Issue: very small pool of preambles available (preambles designed for very big cells up to 100 km)- Options under investigation:

- adapt LTE PRACH preambles using more cyclic shifts (at the cost of higher missed detection rates and false alarms) - apply different root sequences at the cost of mutual interference (between different roots), - m-sequences at the cost of higher PAPR,- CDMA codes at the cost of requiring high synch accuracy.

- Alternative approach: ‘shape’ arrival distribution- slot access principle (map access opportunities to device ID – i.e. a given device is

only allowed to transmit in predefined sub-frames) at the cost of increased latency

- Performance boost (future work):- MUD for collision resolution

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Flexible frame design and radio resource management

• As indicated earlier, one of the key targets is to enablethe frame to be able to carry allocations with different configurations optimized for the respectiveservice/link/device characteristic. This includes aspects of:

- Radio resource management- provision of a set of resource block configurations (from ultra-short

for low latency services to very long for e.g. coverage extension)

- Waveform design- Allow signal transmissions with less tight time/frequency alignments- Enable the possibility to adjust the subcarrier spacing per allocation- Optimize the filter characteristic according to the respective connection

- Control channel design (DL)- Avoid shared control channels- Data and its related control should share the resources

In-resource Control Channel (CCH) with downlink scheduling grant.

Downlink data payload

CCH content summary:- UE identifier- PHY configuration for data payload.

- HARQ information- MIMO information

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Extension of the FANTASTIC-5G air interface to specialized scenarios andextreme cases

• Phase 1 of horizon2020 is focused on designing a highly flexible air interface to support theanticipated heterogeneity forseen in 2020

• Follow up actions apply the outcomes of phase 1 to specialized scenarios and extreme cases

- Satellite communications- increased round-trip-time requires adapting feedback loops (e.g. HARQ)- different channel conditions possibly requires adaptations on waveform and frame design

- low ARPU areas- ultra low-cost to be emphasized, e.g. by cutting down the system to only essential functionalities and by higher interside-

distances

- Industry 4.0- Extreme case of MCC

- Emergency mode- Fall back mode using (non-network) controlled D2D and BMS features (e.g. to broadcast relevant info about rescue plans)

Phase 1 design targets to ensure forward compatibility to those variants/adaptations.

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Thanks!Questions?