27/05/2014 1 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks

looking ahead to 5G Building a virtual zero latency

gigabit experience

Preben Mogensen, Kari Pajukoski*, Esa Tiirola*, Jaakko Vihriälä*, Eeva Lähetkangas*, Frank

Frederiksen*, Gilberto Berardinelli, Fernando M. L. Tavares, Nurul H. Mahmood, Mads Lauridsen, Davide

Catania, Martha Sarret, Andrea F. Cattoni, Petar Popovski, Dereje Wassie, Oscar Tonelli, Farhood

Hakhamaneshi

27/05/2014 2 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks

Capacity

Latency

Energy consumption

Cost

User data rates

Coverage

Stretching performance targets for 5G

x more traffic

By 2030

Low energy

M2M ultra low cost

millisecond

latency

Mbit/s wherever needed

years M2M

battery life Gbit/s peak data rates

x more devices

Ultra reliabilit

y

2020+

27/05/2014 3 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks How to increase Network Capacity towards 5G?

5G will be a HetNet configuration, where each layer will see different factors

Spectral Efficiency

Amount of Spectrum

Number of

Base Stations Capacity

HSPA+

LTE

WiFi

TD-LTE

LTEFemto

HSPA+Femto

Macro

Small Small

UDS

UDS

UDS

Spectral

efficiency Spectrum

Base

Stations Capacity

x x

Ultra dense small

cells

Small cells

Macro cells

+

+

TOTAL Size of boxes only indicative

27/05/2014 4 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks New Spectrum - for 5G ultra dense small cells

Carrier Frequency

Single Antennas

(or low efficiency)

Multi Antenna

Technology

(High Rank)

Multi (massive)

Antenna Technology

(Low Rank)

LOS/NLOS LOS (single reflection)

5G must be flexible in supporting new spectrum:

(cell range, carrier frequency, system bandwidth and antenna technologies)

?

dm-waves cm-waves mm-waves

3GHz 30GHz

mm-wave

5G RAT cm-wave

5G RAT Current IMT

RAT’s

Basic Link budget / Cell size

Spectrum

Availability

300GHz

27/05/2014 5 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks How to Increase Spectral Efficiency for Ultra Dense Small cells?

Multi Antenna Systems and advanced receivers: • Commercial evolution of multi antenna technology has gone slow in past but ease with higher carrier frequency

• Receivers with interference rejection/cancelation capability has great potential but increase base band processing complexity

Interference coordination

• Minor or no gain in average

• Large Improvement in outage

Single link optimization

• Single link capacity is already close to Shannon:

• Fast adaptive modulation and coding

• Hybrid ARQ

Claude Elwood Shannon (1916–2001)

Small potential Medium potential Large potential

27/05/2014 6 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks

• 5G will only become a success, if we choose the right technology for the right

time and purpose.

From H2020 vision to 5G realistic targets

Performance Optimized Cost and Energy Optimized

?

27/05/2014 7 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks 5G cm-wave RAT optimized for ultra dense small cells

cmWave design targets

Less than 1ms latency

Flexible operation in unpaired bands

Self-optimized APs

”Always on” w/o battery draining

Multi-hop, D2D & self-backhaul

10 Gpbs peak data rate

Simplicity & cost-effectiveness

Native location services support

High rank MIMO

Interference suppression

OFDM modulation

Optimized frame structure

Interference coordination

Dynamic TDD

Distributed synchronization

Scalable carrier bandwidth

Design solutions

“Always ON”, low overhead

Flexible support of

UL/DL traffic patterns D2D

Multi-hop

Self- backhauling

Low cost

Low power consumption

Location information

Internet cloud

27/05/2014 8 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks Duplexing - for 5G ultra dense small cells

• Flexible spectrum assignment

• Ease of spectrum sharing

• Flexible UL/DL duplexing

• Simple RF ->Low cost

• Low power consumption

• Channel reciprocity

• Ease of support: normal access, self-backhauling and D2D

• TDD is an attractive duplexing scheme for 5G

ultra dense small cells

Internet Clod

27/05/2014 9 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks

• Higher data rates requirements shorter

latency to reduce cost of baseband (especially

buffering)

5G: Higher Carrier bandwidth and shorter TTI

Fractional cost breakdown relative to baseband for

reference FDD/LTE modem [R1-120925]

Receiver data processing

HARQ buffer

Post FFT buffering

ADC/DAC (DFE)

Sync. Cell search

Turbo Decoding

MIMO specific processing

UL Tx Processing

FFT/IFFT

Receiver control processing

TTI length

3G

4G

LTE

5G

Carrier

Bandwidth

• Multi-Gbps data rates and milliseconds latency

27/05/2014 10 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks Are there quantum leaps in Waveforms?

OFDM, FBMC, FTN

Heisenberg tells us:

Whatever we gain in one domain, we are doomed to lose in the other:

• OFDM is localized well in time but not well localized in frequency

• And vice versa with FBMC or other frequency optimized modulations

There are various options to trade

time vs. frequency confinement, but

there is no free lunch

Low latency requirements & low complexity high rank MIMO

seems to favor OFDM also for 5G

27/05/2014 11 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks

.

0 10 20 30 40 50-80

-70

-60

-50

-40

-30

-20

-10

0

10

Bandwidth [MHz]

Po

we

r [d

B]

DFT-s-OFDM

zero-tail DFT-s-OFDM

Zero Tail: Create an OFDM symbol having a number

of zeros at its termination.

Zero-tail DFT-S-OFDM as flexible waveform for 5G

Advantages:

• Allows to use link specific “Zero” length

• Better spectral containment compared to DFT-S-OFDMA or OFDMA

• Lower PAR compared to OFDMA

• Can be applied to take care of Guard Period

• Can be applied for D2D communication in order to mitigate asynchronous inband interference between D2D and cellular communications

• Can fully coexist with CP-OFDMA

One merit of OFDM is flexibility for diversity use cases: SC-FDM, as well as zero-tail DFT-S-OFDM can

be obtained as straightforward add-on over basic OFDM.

dataDFT

zeros

0

IFFTSub-

carrier

mapping

0 0

CP

27/05/2014 12 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks

Support for advanced receivers

Flexible UL/DL, D2D and self- backhauling

Energy-effective pipeline processing

Frequency coordination and reuse

Control channel located before data

5G Optimized frame structure for Ultra Dense Small Cells Flexibility, lower latency and higher throughput

DMRS = Demodulation Reference Signal; GP = DMRS = Demodulation Reference Signal; GP = Guard Period

Stabilized covariance matrix of interferers

Control plane localized in time & frequency

DL and UL have same PHY (control, data, RS)

Fre

quency

Time

Control Data (entirely DL or entirely UL)

GP OFDM symbol GP

DL UL DMRS

0,25ms

GP

27/05/2014 13 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks Advanced Receivers for MIMO

to overcome the interference problem

MRC Maximum Ratio Combining

Inter-cell interference unaware MIMO linear receiver

IRC+SIC

Interference Rejection Combining

Interference aware MIMO linear receiver

IRC + Successive Interference Cancellation

Non-linear MIMO receiver that cancels inter-stream interference

IRC

27/05/2014 14 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks MIMO and Advanced Receivers

Further performance improvement using IRC+SIC C

DF

(%

)

0 1000 2000 3000 4000 5000 60000

10

20

30

40

50

60

70

80

90

100

Average Cell Throughput [Mbps]

CD

F [

%]

MRC

IRC

IRC+SIC

0 1000 2000 3000 4000 5000 60000

10

20

30

40

50

60

70

80

90

100

Average Cell Throughput [Mbps]

CD

F [

%]

IRC - Reuse 1

IRC+SIC - Reuse 1

IRC - Reuse 2

IRC+SIC - Reuse 2

4x4, reuse 1 4x4, reuse 1 & 2

27/05/2014 15 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks 5G: MIMO and Advanced Receivers

System design requirements

OFDM symbol-level network synchronization

IRC

Identical uplink and downlink frame formats

Orthogonal reference symbols for interference estimation

Interference stabilization during the frame

Interference-aware rank adaptation

Independent MCS block coding per layer

SIC-aware link adaptation

IRC+SIC

Interference-aware rank adaptation

SIC-aware link adaptation

27/05/2014 16 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks Rank adaptation – dynamic selection of the number of MIMO streams

Challenges Solutions

Estimating expected

throughput in fast changing

interference conditions

Efficient and novel post-IRC

SINR estimation method that

does not require instant CSI

Maximizing own throughput is

selfish:

→ Increases interference

→ Reduces DoF for IRC

Victim-awareness (VA) through

cooperation:

→ Altruistic rank selection

→ Improved network SE

Instant

CSI Victim-Aware Non VA

Yes → Optimum performance

→ Practically impossible

→ Difficult in practice with

flexible UL/DL

→ Poor performance

No

→ Proposed algorithm

→ Close to optimum perf.

at lower complexity

→ Uses post-IRC SINR

estimation method

→ Similar performance to

instant CSI

Rank adaptation trade-off

More streams:

↑ Own throughput

↑ Interference

↓ IRC DoF

Less streams:

↓ Own throughput

↓ Interference

↑ IRC DoF

0 5 10 15 200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Spectral Efficiency (bps/Hz)C

DF

Four cells, 100% deployment ratio

Optimum

Proposed VA

Proposed non-VA

Instant CSI, non-VA

Fixed Rank (1)

Fixed Rank (2)

Fixed Rank (3)

25%

27/05/2014 17 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks Concept emulation: 5G performance with ultra dense small cells

Fixed TDD pattern -50%

Fixed TDD pattern

Latency

+30%

Throughput

UL/DL switching

Interference suppression

Interference coordination

Fast dynamic UL/DL switching for optimal

resource utilization

Multi-antenna technology, advanced receivers, and rank

adaptation

Self-organized fractional reuse for

interference avoidance

Dynamic UL/DL switching

Dynamic UL/DL

switching

27/05/2014 18 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks Dynamic UL/DL switching cause Interference variability Time trace for a single UE, full buffer

Assuming perfect reporting

Evaluating the difference between SINR at time of reporting and

SINR at time of scheduling

Fixed 1:1

UL/DL

Random

50 100 150 200 250 300 350 400 450 5008

10

12

14

16

18

20

22Random pattern

SIN

R

time

50 100 150 200 250 300 350 400 450 5008

10

12

14

16

18

20

22Fixed pattern

SIN

R

time

27/05/2014 19 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks Can we overcome the interference variability from dynamic UL/DL? H-ARQ, OLA, Low Rank….

Lost

capacity HA

RQ

Lost packet We monitor the SINR (CQI) at

time of reporting and the SINR

when scheduled and compute the

difference.

Negative values means lost

capacity potential

Positive values means packet

error.

27/05/2014 20 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks The ”beast” of RRM for 5G is becoming complicated

RRM

buffer size

delay

QoS

data

ACK-NACK

CQI

CSI

radio

Users

direction

H-ARQ

MCS

RANK

PMI

Frequency

allocation

out

User selection

Link adaptation+

OLA

H-ARQ

Link direction

Interference Coordination

Rank adaptation

27/05/2014 21 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks 4 Cell Testbed Demo @ Aalborg University

Based on USRP N200 hardware

by Ettus Research and ASGARD

software platform

1 2

3 4

2x2 MIMO, RANK 1

27/05/2014 22 © Nokia 2014 - Looking ahead to 5G

For internal use

FutureWorks

Lets shape 5G together.. “It is dangerous to put limits on

wireless” (1932)

-Gugliemo Marconi