paradigm shifts in rf testing beyond lte: lessons learnt ... · pdf fileoptimisation &...

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Title:

Paradigm shifts in RF testing beyond LTE: Lessons learnt and challenges ahead

Narrative:Cobham Wireless has been the market leading network infrastructure test solutionprovider since 3G, LTE to 4G. We are the thought-leader in enabling development toolsand test technologies for wireless technology researches and advancements. We willshare our experiences, observations and thoughts on the paradigm shifts and conceptchanges in the testing of the generation defining RF and wireless technologies beyond4G towards 5G.

Bio:Li-Ke Huang is the Research & Technology Director at Cobham Wireless responsible forproduct concept and core technology innovations. He specializes in leading earlytechnology research programs for the TM500 network tester family, which is theindustry standard wireless network tester used by network operators and infrastructurevendors worldwide.

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Paradigm shifts in RF testing beyond LTE: Lessons learnt and challenges ahead

• TM500 product family: De facto network infrastructure test solution

• T&M’s view of Wireless Technology Advancements

• Thoughts on wireless system R&D paradigm shifts

• Examples of current & future T&M challenges

Li-Ke Huang @ Wireless Heritage SIG, 19th February 2015, Stevenage

2/20/20152


TM500 product family

De facto network infrastructure test solution and development tool

2/20/20153

UbiNetics => Aeroflex => Cobham Wireless(2000) (2006) (2014)


15 years’ enabling ‘generation defining’ technologies

TM500

▼Always 1st to market 3GPP features

▼Enabler for wireless technology advancements solving all kinds of eNB network R&D problems

▼Thought-leader in wireless T&M technologies & development tools

▼Active researcher in 4G evolution towards 5G

GSM•GMSK•Viterbi

•Speech codec

•12.2k

1990

UMTS/R99•WCDMA

•Tubro•Power control

•356k

2000

HSDPA•HARQ•14Mbps

2004 2008

LTE•OFDM

•FC-FDMA

•2x2 MIMO•50Mbps

LTE/R8•4x4 MIMO

•300Mbps

•TDD

2014

LTE-A (4G)•Carrier aggregation•UL-MIMO

•eICIC

•Relay

2011 20202006

Release 11/12

•CoMP•TDD/FDD

•feICIC•256QAM•iRAT

•3CC

•Dual conn.

LTE/R9•Dual layer BF•Positioning

•eMBMS

20182016

5G

C-RANSDN

mmWave

CDN

Massive-MIMO

HetNetLAA

LTE-U

SON

IoT

D2D

MSA

Artificial intelligent

??SDAI

3D-MIMO

NFV

MEC

Fog-computing

NA-IC

Wifi-offload

Cobham plcCobham plcAeroflex Confidential2/20/2015

15 years of wireless T&M technology platform development

2009LTE SUE & MUE

HSPA+

2010-2012HSPA+ MUE

LTE SUE, Ext-MUE,

LTE Capacity test

LTE-A PoC

Oct 2008

Platform C

LTE SUE

2003 –

TM500

Platform A

HSDPA SUE & MUE

1999 –

TM100

R99 - 384kbps

2007

Platform B

HSPA+ SUE & MUE

LTE PoC

SYSTEMS

2013-2014

Latest Hardware12,000 UE capacity

HSPA Ext-MUE/capacity

LTE-A & Rel-11/12

HSPA Rel-105G

Virtualised


Wireless technology development cycle

Research & PoC

Standardisation & specification

Design & implementation

Production & deployment

Optimisation & evolution

Increased expectation => new market & technology drivers

4G+

5G

Enabling development tools and test solutions at every stage

Lesson learnt & new challenges

• R&D cycle speeding-up and R&D stages merging

• Paradigm shifts in system architecture & design flows

• Increasing customer/market expectations

• Incorporating innovative technologies from all domains


R&D race beyond 4G (LTE-A) towards 5G

2/20/20158

2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

R14 (5G) R15 R16

R14 R15 R16R13

3GPP/5G

3GPP/4GFocal point for technical spec.

Vision Requirements/Methods Wkp Proposals

ITU

Evaluation

IMT-2020

specifications

METIS/5GNOW 5GPPP (spec) 5GPPP (dev) 5GPPP (exp)

EU

Start up Vision Research Test-bed

UK/5GIC

Winter Olympics in South Korea

Summer Olympics in Japan


Our observation

How T&M to enable wireless technology advancements

2/20/20159

Time

Com

ple

xity &

sca

le

System under test

Test system

Research & PoC

Advanceddevelopment

Full scale development & deployment

5G is here.(today’s technologies tomorrow’s problems)

4G is here.

Lessons learnt:▼ T&M should progress with SUT▼ Test the weakest link▼ Test real-life network scenario▼ Anything can go wrong will go wrong▼ Make/expect mistakes and make them early


Cobham Wireless (Aeroflex) research cooperation with 5GIC

• UK’s 5G research leadership with ProfRahim Tafazolli of 5G Innovation Centre(5GIC) in Surrey University

• Aeroflex (Cobham) is founder member of5GIC along with AIRCOM, Ascom, BBC,BT, EE, Fujitsu, Huawei, R&S, Samsung,Telefonica and Vodafone

• 5GIC’s technological vision of achieving‘perceived’ infinity network capacity fromend users’ point of view

• ‘Real-life’ 4G+ to 5G test bed to bedeveloped in Surrey University with joinedefforts from all partners

10


Aeroflex (Cobham) technologies and capabilities

enabled 1st 5G air interface demo on MWC2014

• TM500 platform for 5G technology researches

• FBMC/IOTA modem selected as 1st example

• Downlink physical layer design within LTE framework

• Development & test tools to evaluate KPIs with system design gains

• Framework for converting theories to practices

2/20/201511


Cobham Wireless (Aeroflex) 4G+ PoC technology demos in 2014/2015

• 256QAM demo on TM500 in InternationalMobile Internet Conference 2014, August,Beijing.

• feICIC receiver demo with test intelligentgeneration and control on TM500 inGlobelcom 2014, December, Austin.

• 5G candidate waveform with FBMC/IOTAscheme on TM500 in cooperation with 5GICin Mobile World Congress 2014, February,Barcelona.

• Generalised Non-orthogonal waveform demowith 5GIC/Cobham in MWC 2015, March,Barcelona.

Come and visit us on MWC 2015!

2/20/201512


5G disruptive capability targets

Quantifiable targets:

• 1000x traffic volume (> 10 Tbps/km2)

• 1000x number connected devices (> 1 M/km2)

• 100x peal terminal data rate (>10 Gbps)

• 1/10x energy per bit (compared to 2010)

• 1/10x end-to-end latency (<1 ms)

• 1/10x physical layer latency (<0.1 ms)

• 1/10x OPEX

• 1/1000x service deployment time (<90 min)

• Minimum guaranteed terminal data rate > 50Mbps

• Human terminal > 20 billion

• IoT terminal > 1 trillion

• Service reliability > 99.999%

• Mobility > 500km/h

• Outdoor terminal location accuracy < 1m

2/20/201513

Non-quantifiable targets:

• Software defined architecture

• Simplified authentication

• Shared infrastructure

• Multi-tenancy

• Transparent multi-RAT

• Interception capacity

• ICT design principle integration

• OTT integration

• Network service as a service

• Integrated front-haul and back-hual

• CPRI over packet

• Unified network elements

• Single digital market


Spectrum allocation for future wireless systems

2/20/2015

Proprietary14

6 GHz 100 GHz

Primary band mmWave band

Primary band

• Dynamic spectrum access

• Integration with latency RAT

• Programmable air interface

• New waveforms

• Proven RF technologies

• Spatial processing technologies

• 15 bps/Hz => 100 bps/Hz

mmWave band

• New RF technologies

• Limited range and mobility

• High frequency & BW

• Array beamforming

• 10~20 bps/Hz

• Integrate with primary band

• Longer term efforts


Our summary

Trends & Drivers in Wireless Technology Advancements

• 2G, 3G, LTE and 4G mostly defined by their Air Interface

• FCC’s generation definition: waveform & frequency

• Future generations: service, infrastructure and user prospects

• Use any frequency band and any RAT (DSA and cognitive network)

•HetNet = fusion of multitude complex technologies & topologies

• Co-operative and intelligent network

•Space: the next frontier

• Large scale, dense and flexible ’elastic’ system’

• Network management (system orchestration) will be the key

•New and advanced KQIs and KPIs

• System centric design, but physical layer (air interface) is NOT dead

15


T&M challenge #1: What are we testing?

eNB

eNB

EPC

3G/LTE handover with MIMO



eNB eNB

EPC

X2

4G+ Downlink CoMP (rapid cooperation is the feature under test)

EPC

eNB

eNB

X2

System under test (2 2x2 point CoMP )

TX1TX2RX1RX2

CPRIA2

B2

C2

D2

TX1TX2RX1RX2

CPRIA1

B1

C1

D1



RRH RRH

EPC

Evolution underlying architecture (centralised & software defined)

eNB eNBX2

C-RAN

RRH

eNB

X2

RF/CPRI switch

Software defined entities that can be

dynamically reconfigured(system Orchestration)



RRH RRH

Evolution underlying architecture (flat and unified network elements with virtualised functions)

eNB eNB

X2

C-RAN

RRH

RF/CPRI switch

EPC EPC

Network management

eNB

EPCX2

eNB

EPC

D2D link

Virtualised EPC/eNB functions on UE platform

Hybrid-eNB



• Dynamic & reconfigurable (testing a moving target)

• Software defined ‘everything’

• Xaas = Cloud computing concept (Test as a service)

• Self ‘everything’ (self-testing)

• Virtualised functions on programmable unified network elements

• Converged architecture diverged services

• Centralised distributed

Summary of key prosperities of future ‘system under test’

2/20/201520


T&M challenge #2: System and test complexity

2/20/201521

Test Orchestration

• Physical connection to SUT non-defined or not possible

• Not possible for manual testing with the increasing system complexity and new KPIs (e.g. QoE)

• Complex simulation and modelling to create a useful test cases

SUT

Network operator, tester, engineer, researcher or other machines

T&M


T&M challenges #3: How to test the ‘tester’

2/20/201522

SUT T&M

• Joined & shared R&D• Layered testing • New test interface• Early integration (e.g. ref model)

•Chicken & egg

•Both SUT and T&M are new for very complex features

•Traditional signal generation and signal analysis will not be sufficient

•New approaches in design & test flows


Discussion by examples:

Integration of air interface, network topology, RF and system technologies development & test complexity

•Interference limited transceiver

•HetNet with feICIC

•CoMP/MU-MIMO/MU-beamforming

•RF array front-end

•3D-MIMO

•Massive MIMO & C-RAN

2/20/201523

Cobham plcCobham plc24

– LTE/HetNet interference limited – cell edge effect

– ICIC = Network management & coordination

– Almost blank sub-frame (ABS)

– Cell reference signal (CRS) becomes main interference resources

– Range expansion 9dB => offloading more UE to small cells

– UE interference cancellation (network assisted)

Interference limited transceiver (1)


Realistic HetNet cell-edge interfere modelling (1)

2/20/201525



2/20/201526



2/20/201527



System gains and KPIs to evaluate:– Cell edge area reduction

– Small cell range extension

– Traffic offloading to small cell

– UE interference cancellation

– Inter eNB coordination efficiency

– CAPEX and OPEX efficiency

SINR (range)

Throughput

90%

KPI: 1 dB gain reduces ~14% CAPX


Transceiver design covers:

(A) All aspects of info theory and wireless system engineering

(B) The problem cannot be solved in a single domain:

(1) Symbol rate signal processing

(2) Bit rate processing

(3) System & protocol signalling and control

FFT

FFT

RX-1

RX-2

Symbol rate

processing

IC ControlRSRP/

RSRQ

Ctrl

New blocks

SRP

Interference

Cancellation

BRP

Interference

Cancellation

Bit rate

processing

Ctrl

Neigbour cell

info from cell

search

Main data path

Ctrl and signalling

RF




Before After

Interference

level reduced;

comparable to

noise level



Low MSC noise

dominating for

SIMO

Significant gain for

low MSC MIMO

-10 -5 0 5 100

1

2

3

4

5

6

7SIMO,EVA5,MCS=8

SNR

Thro

ughput(

MB

ps)

IC

reference

w/o IC

10 12 14 16 18 20 220

5

10

15

20

25

30

35SIMO,EVA5,MCS=26

SNR

Thro

ughput(

MB

ps)

IC

reference

w/o IC

0 5 10 15 200

2

4

6

8

10

12

14MIMO,EVA5,MCS=8

SNR

Thro

ughput(

MB

ps)

IC

reference

w/o IC

12 14 16 18 20 220

5

10

15

20

25

30

35MIMO,EVA5,MCS=16

SNR

Thro

ughput(

MB

ps)

IC

reference

w/o IC

SIMO

2x2 MIMO

Transceiver validation alone will not be sufficient to evaluate feICIC from the system point of view.


HetNet with feICIC (1)

2/20/201532

Test must be in context

Cell topology

Interference modelling

Number of UE

UE mobility

eNB coordination



2/20/201533



2/20/201534

New KPIs

Cell range extension factor

Fall back success rate

UE offloading rate

T-put gains

eNB coordination accuracy

New ones that are not defined today



2/20/201535

New test cases

Relate traffic & interfere

UE mobility

Hot-spot

Negative testing



2/20/201536



2/20/201537



2/20/201538


RF array front-end (0)

TX1TX2TX3TX4TX5TX6TX7TX8

CPRI

A

B

eNB#1

eNB#2

X2

System under test (Show only DL)

C

D

b

d

a

c

TX1TX2TX3TX4TX5TX6TX7TX8

CPRI

E

FG

H

f

h

e

g

A

B

C

D

a

b

c

d

eNB#1

Spatial channel

between UE#1

and eNB#1

Spatial channel

between UE#1

and eNB#2

eNB#2

Array-1: A, B, C and D

Array-2: a, b, c and d

Array-1 and Array-2 for dual-layer MIMOMultiuser and dual layer beamforming scenario

Real life dual layer array

deployment for LTE

network (2 x 4-element

array)

Normal 2x2 MIMO

antenna

configuration



2/20/201540

Beamforming system design challenges

Multi-channel RF

Phase coherency

Beamforming

time and frequency domain

Digital & analogy domain

Single user and multi-user

Peak/null steering



2/20/201541



2/20/201542



2/20/201543


Array error modelling & measurement (1)

2/20/201544


Array error modelling & measurement (2)

2/20/201545


CoMP & Multi-user beamforming/MIMO (1)

2/20/201546

Co-channel deployment

UEs use different RB

eNBs scheduler design



2/20/201547

More frequency reuse

UE location dependent

High density cell and high density Ues

Interference limited system efficiency



2/20/201548

Deploy BF array for each eNB



2/20/201549

If eNBs start to cooperate …


Example of network infrastructure test challengesTest case # 2: CoMP & Multi-user beamforming/MIMO (5)

2/20/201550

Tracking and steering both peaks and nulls …


Example of network infrastructure test challengesTest case # 2: CoMP & Multi-user beamforming/MIMO (6)

2/20/201551



2/20/201552

• Negative test to validate the limit of the technology so that we can improve …

• MU-MIMO and CoMPexpected to provide 10x T-put gain for LTE

• CoMP demos enabled by TM500 on MWC 2015


3D-MIMO (1)

2/20/201553


3D-MIMO (2)

2/20/201554


3D-MIMO (3)

2/20/201555

T&M challenges

• Large number of RF channels

• Integrated antenna and RF front-end design

• Hybrid RF and digital beamforming


5G T&M use case: How to evaluate Massive MIMO system performance sufficiently

2/20/201556

Centralised and virtualised processing resources

C-RAN

Massive MIMO (Smart Tiles)

Narrow 3D beam

UE

UE

CPRI

HetTest interface

Advanced Network Test Solution

• Intelligent test case simulation

• End to end traffic generation

• Corner case and negative test

• KPIs evaluation

UE

UE

UE


Recap: T&M challenges for future wireless systems

• SUT will be abstract, virtualised, dynamic and large scale

•Design paradigm shifts demand new test archs/methods

• ‘Testability’ & ‘debuggability’ inherent to system design

•RF, AI, protocol testing must be in context

•Redefine physical connection to test equipment

• Produce/model real-life scenarios with new KPIs

• Critical to test the ‘tester’

57


Thank you and we believe

Challenges = Opportunities

Questions, ideas, discussions, suggestions and cooperation's are welcome.

2/20/201558

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