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A LOOK INTO THE FUTURE OF

NEXT-GENERATION WIRELESS

NETWORKS

Khaled B. Letaief

Dean of Engineering

HKUST

Dhahran, 18 December 2012

1


Outline

• Brief Introduction to HKUST

• Wireless Evolution

• B4G systems

– Drivers

– Challenges

– Potential Technologies

• The Next Wireless Revolution

→Towards the Internet of Things

• Conclusions

2

2


Located at the edge of Southern China

Hong Kong


Hong

Kong

University of

Science and Technology

• OPENED IN 1991

• 10,000

000 STUDENTS, 500 FACULTY

• ALL ENGLISH INSTRUCTION

• RESEARCH INTENSIVE UNIVERSITY

4


5

050624CWC


The School of Engineering

SENG

Electronic and

Computer

Engineering

ECE

Computer

Science and

Engineering

CSE

Chemical and

Biomolecular

Engineering

CBME

Civil and

Environmental

Engineering

CIVL

Industrial Eng.

and Logistics

Management

IELM

Mechanical

Engineering

MECH

E 2 I

Computer

Engineering

CPEG

Bio-Engineering

Environmental

Engineering

Inter-disciplinary

Research

Programs

Nano Technology

Sustainable

Energy

82


World Rankings for HKUST

2006 2007 2008 2009 2010 2011 Sources

- - - 4 2 1

QS Asian University

Rankings

HKUST

- - - - 40 -

58 53 39 35 41 -

Technology 17 23 24 26

QS World University

Rankings

Times

Higher Education

Supplement

26 20 -

Times

Science 69 52 59 62 43 -

Life Sciences 61 80 67 70 50 -

Higher Education

Supplement

MBA 47 - 17 16 9 - Financial Times

EMBA 3 1 2 1 1 - Financial Times

9


Engineering Latest 2012

QS World University Subject Rankings

Subject 2012

Computer Science 13

Chemical Engineering 20

Civil Engineering 18

Electronic Engineering 17

Mechanical Engineering 19

HKUST #1 University in Asia (QS Ranking)

HKUST World # 3 young university under 50

(TimesHigherEd)


• B4G systems

–Drivers

–Challenges

Outline

–Potential Technologies

• The Next Wireless Revolution

→Towards the Internet of Things

• Conclusions

11


Today’s Wireless Communications

• Wide-spread Wi-Fi

– Hotspots becoming ubiquitous

– Progressing standards for higher

throughput

• But, coverage and capacity will always be

an issue

• Evolved Cellular

– Increasing capacity and performance

– Bps/square meter still remains relatively

low

• High Density Broadband Wireless

12


Mobile Communications

• 60 countries with penetration > 100%

• UAE penetration is over 233%

• 4 Billion unique users with accounts and phones (2010)

- 2011

China's mobile phone subscriptions top 1 billion (March 2012)

14


Tomorrow's Communications

Billions of connected

people

Main growth in mobile

subscriptions from new

growth markets

5 Billion mobile

subscriptions

Majority can be always

online via mobile

high-speed Internet

access technologies

0.8 Bn broadband

subscriptions

Wireline Broadband will

facilitate usage of

applications like IPTV

for about 2 Bn people

Source: Nokia Siemens Networks estimations based external forecasts (Ovum, Strategy Analytics)

23


Examples of Factors that will drive Traffic

• 3D internet with

high definition

• Mobile 3D

projector

• Telepresence

• …

24


Examples of Factors that will drive Traffic

25


Moore’s Law

“…… the number of transistors on a chip

approximately doubles every 24 months ...”

— Gordon Moore 1975

26


Edholm’s Law

Edholm’s Law states:

– Wireline, nomadic and wireless data rates are progressing at different

slopes, but are advancing in lockstep

– A given application that requires a specific amount of bandwidth can

transition from wireline links to nomadic links to wireless links as time

progresses and technology advances

Bandwidth

(Exponential Scale)

1G

100M

10M

1M

100K

10K

1K

Messaging

Wireline

Nomadic

Wireless

Web

Pages

Voice

1995 2000 2005 2010


Evolution of Wireless Systems

LTE HSPA EDGE

Evolved EDGE

DL: 1.89 Mbps

UL: 947 kbps

Rel 8 HSPA+

DL: 42.2 Mbps

UL: 11.5 Mbps

10/5 MHz

Rel 8 LTE

DL: 300 Mbps

UL: 45 Mbps

20/20 MHz

Rel 9 HSPA+

DL: 84 Mbps

UL: 23 Mbps

10/10 MHz

Rel 9 LTE

DL: 300 Mbps

UL: 45 Mbps

20/20 MHz

Rel 10 HSPA+

DL: 168 Mbps

UL: 23 Mbps

20/10 MHz

Rel 10 LTE

DL: 1.2 Gbps

UL: 568 Mbps

40/40 MHz

Rel 11 HSPA+

DL: 336 Mbps

UL: 46 Mbps

40/10 MHz

Rel 11 LTE

To be completed

by the end of

2012

CDMA2000

EV-DO Rev B

DL: 14.7 Mbps

UL: 5.4 Mbps

5/5MHz

EV-DO Advanced

DL: 14.7 Mbps

UL: 5.4 Mbps

5/5MHz

Fixed

WiMax

Fixed WiMAX

Mobile

WiMax

WiMAX Rel 1.0

DL: 46 Mbps

WiMAX Rel 1.5

UL: 4 Mbps

10 MHz 3:1 TDD

Source: 2012 Rysavy Research, LLC

WiMAX

IEEE 802.16m

DL: > 1Gbps

29


Evolution of Cellular Systems

f

t

FDMA

Analog、

Circuit Switch

TACS

AMPS

t

f

f

t

CDMA

Broadband、

TDMA Packet Switch

Digital、

Circuit Switch WCDMA

GSM

CDMA


Global Mobile Data Explosion

Global Mobile Data Traffic, 2009 to 2016

12

Exabytes per Month

10.8

10

8

6.9

6

4.2

4

2.4

2

0.09 0.24

0.6

1.3

0

2009 2010 2011 2012 2013 2014 2015 2016

Source: Cisco VNI Mobile, 2012

31


Global data traffic growth ~ 2X

(133% increase) in 2011, for the fourth

year in a row

160%

140%

120%

100%

80%

1000 x

by

2020

60%

40%

20%

0%

10

2 ≈1000

2009

2010

2011

2012

2013

2014

Source: Cisco VNI Mobile, 2012

32


How do we address anticipated acceleration in high

data traffic and demands for rich multimedia content

along with hyper-connectivity

expectation?

Wireless

High Level of

Service Quality

& User Experience

Must meet the projected

1000x data challenge

IP Society

Beyond 4th Generation

Uniform

Connectivity

Experience

Throughout

the Network


1000

Capacity ?

Required Performance ~ 1,000 x

1. Efficient Spectrum

use

(New/Re-farmed

Spectrum)

Current Performance

2. Increase

Spectral Efficiency

(Air Interface)

3. Higher

Average Cell Density

(Small Cell HetNet)

34


1. Efficient Spectrum use

New/Re-farmed Spectrum?

35


Cognitive Radio to Improve the Spectrum

Utilization Efficiency

Power

Frequency

Spectrum in use

Dynamic

Spectrum Access

Spectrum Hole

Time

36


Challenges and Research Topics

• Spectrum Sensing

Detect primary transmitters

operating at different power levels,

bandwidths, and locations

Incentive for collaboration



Management and Architecture

Distributed coordination

Local decision vs. global optimization

Primary

Rx

Primary

Tx

Primary System

Spectrum managements

Resource allocation to support different QoS

Seamless service with varying spectrum conditions

Spectrum Sensing

Cognitive Radio System

Secondary

User

Interference measurement at the primary receivers (sharing schemes)

• Real deployment

– From hardware (cognitive radio-enabled devices) to system

• Security

• Etc.

Secondary

Receiver

37


New Spectrum

Around 60 GHz

communication

Terahertz

technology


Electronics

Photonics

Microwave

mm wave

Sub mm wave

Infrared

Visible

Ultraviolet

0.001 0.01 0.1 1 10 100 1000

GHz

(frequency)

THz

(frequency)

Mobile

phone

Microwave

oven

Infrared

heater

DVD

system

38


New Spectrum: Millimeter Wave Communications

FTTH

TV

Millimeter wave system

phone

PC

printer

39


New Spectrum: Terahertz Communications

40


2. Increase Spectral Efficiency

• Large scale MIMO/Multiuser MIMO?

• Efficient Modulation Schemes?

• Interference Mitigation/Management?

• Spectrum reuse via Multi-cell

cooperation?

• Spectrum reuse via D2D D cooperation?

41


Higher Spectral Efficiency

Higher-Order Modulation

or New Modulations?

Coordinated Multiple Point

(CoMP) Transmission & Reception

Spectral

Efficiency

Interference Management

In Heterogeneous Networks

Massive MIMO &

3D MIMO

Critical when cell density

is high!


Higher Spectral Efficiency: Interference in HetNet

Interference:

• From Marco cell to Femto/Pico/Relay cell

• From Femto/Pico/Relay cell to Marco cell

• Between Femto/Pico/Relay cells


Higher Spectral Efficiency: Interference in HetNet

Solutions:

• Smart resource reuse

• Power control

• Advanced receivers (IC)

• Autonomous carrier-based

interference management

• CoMP techniques

• Interference alignment


Cooperative Communications

"Coming together is a beginning.

Keeping together is progress.

Working together is success."

-- Henry Ford

Virtual MIMO

Relay

• Many possible cooperation strategies:

• Virtual MIMO, relaying (DF, AF) and network coding

45


Cooperative Communications in Cellular

Femtocells

Relay

Many open problems

for next-gen systems

• Network MIMO: Cooperating BSs form a MIMO array

– Downlink and uplink are multiuser MIMO channels

– Can treat “interference” as known signal (DPC) or noise

– Can cluster cells and cooperate between clusters

– Can also install low-complexity relays and/or Femtocells

• Mobiles can cooperate via relaying, virtual MIMO, analog

network coding, …

46


CoMP: Coordinated Multiple

Points Transmission

CoMP

Het-Net

Relay

47


Coordinated Multiple Points

Transmission

• Interference Coordination

– Eliminate interference by coordinating

transmission/reception of multiple access points (APs)

• Base station coordination, multi-cell processing, CoMP in LTE-

Advanced

Interference

Coordination

48


Two Different Approaches

Coordinated Single-cell

Transmission

Coordinated Multi-cell

Transmission

• Data is transmitted from a single

AP

• Interference is cancelled

• Applicable when data is not

available at different APs

• Data is transmitted from multiple

APs

• No interference with joint

transmission

• Applicable when data is available

at different APs

49


Inter-Cell Interference Cancellation (ICIC)

• Spatial ICIC

– Interference cancelled with pre-coding

• CSI training optimization

– Pilot/data power allocation

• CSI feedback optimization

– Feedback for data transmission

– Feedback for interference cancellation

22

Average Throughput

8

Edge Throughput

Average Sum Throughput (bps/Hz)

20

18

16

14

12

10

ICIC w/ perfect CSI

ICIC w/ analog feedback

ICIC w/ digital feedback

No ICIC

5th percentile throughput (bps/Hz)

7

6

5

4

3

2

ICIC w/ perfect CSI

ICIC w/ analog feedback

ICIC w/ digital feedback

8

1

No ICIC

6

0 2 4 6 8 10 12 14 16 18 20

Edge SNR (dB)

0

0 2 4 6 8 10 12 14 16 18 20

Edge SNR (dB)

50


Many Open Problems

Interference coordination under limited backhaul

capacity

Efficient CSI training and feedback

Distributed implementation of interference

coordination

Interference coordination in heterogeneous

networks

Cloud RAN

51


Higher Spectral Efficiency: Interference in HetNet

Solutions:

• Smart resource reuse

• Power control

• Advanced receiver (CRS IC)

• Autonomous carrier-based

interference management

• CoMP techniques

• Interference alignment


Degree of Freedom (DoF) & Interference Channels

Point-to-Point Channel

Interference Channels

Tx

Rx

Tx

Rx

• One interference-free link

• DoF = 1 per user

Tx

Rx

Tx

Rx

• Three parallel interference-free links

• DoF = 3 per user

Tx

Rx

• With conventional orthogonal

(time/frequency division) access

schemes, 3 users share 1 DoF.

• DoF = 1/3 per user

Can we do better?


Interference Alignment: Example

Without Interference Alignment

No signals can be decoded!

(more signals than space dimensions)

2 signals to

transmit by

Tx 1

1 signal to

transmit by

Tx 2

1 signal to

transmit by

Tx 3


Interference Alignment: Example

Note: 3/2 DoFs can be achieved with

infinite channel extensions (e.g., time

or frequency slots) [Jafar ’08].

Without Interference Alignment

All 4 signals can be decoded!

DoF = (2+1+1) / 3 = 4/3 > 1

2 signals to

transmit by

Tx 1

1 signal to

transmit by

Tx 2

1 signal to

transmit by

Tx 3


Limitations of Interference Alignment

• IA highly relies on number of available channel freedoms across spatial, time

or frequency domain. The performance will degrade with

• Constant channel coefficients (e.g., flat fading channels)

• Rank deficient channels (e.g., Line-of-Sight channels)

• Limited number of antennas

Tx

Rx

Tx

Rx

Tx

Rx


Proposed Solution: : Relay-Aided

Interference Alignment

Relay-Aided

Interference Alignment

• Create artificial randomness

• Provide additional channel freedoms

• Neutralize partial interference

Tx

Rx

Tx

Rx

Tx

Relay

Rx

• IA within spatial domain

Tx

• Multiple antennas at each nodes

• Amplify-and-forward relays

Rx

Relay

Tx

Rx

Tx

Rx

Relay


Relay-Aided IA: Example

Interference is aligned by relays

Receivers cannot distinguish the

&

information from interference!

Interference cancellation at

destinations.

1 signal to

transmit by

Tx 1

Relay

1 signal to

transmit by

Tx 2

1 signal to

transmit by

Tx 3

Relay


Relay-Aided IA: Formulation

Pre-coding Matrix Amplifying Matrix Zero-forcing matrix

Equivalent channels:

IA Conditions:


Relay-Aided IA: Results

Solvability of the

polynomial equations

Theorem 1: Any achievable DoF tuple by relay-aided

interference alignment within spatial domain is upper-bounded by:

IA Conditions:


Relay-Aided IA: Performance

Tx

Rx

Relay • 3 antennas at each

nodes

Tx

Tx

Rx

Rx

• 4 Tx-Rx pairs

• Increase the number

of relays

Tx

Relay

Rx


Relay-Aided IA: Performance

12

10

8

Full-Duplex Relaying

Half-Duplex Relaying

• 3 antennas at each

nodes

Sum DoF

6

4

• 4 Tx-Rx pairs

• Increase the number

of relays

2

Direct Transmission

Direct Transmission

with Spatial IA

0

0 2 4 6 8 10 12 14

Number of relays


Relay-Aided IA: Conclusions

• IA can significantly increase the throughput (spectrum

efficiency) with limited bandwidth.

• IA highly relies on the number of available channels and has

some limitations

Relay-Aided Interference Alignment is powerful solution as

additional channel freedoms are provided by the relays.

[Ref] X. Chen, S. H. Song, and K. B. Letaief, “Interference alignment in

MIMO interference relay channels,” in IEEE Wireless Communications and

Networking Conference, WCNC’2012.


3. Higher Cell Density

• Small Cells?

• Heterogeneous networks?

64


Scaling of Capacity: Higher Cell Density

Area Spectral Efficiency of Dense Small Cells

Area Spectral Efficiency: X 20?

Capacity Gain

35

30

Capacity

Femto-cell

25

20

15

Pico-cell

10

Size

Macro-cell

5

0

Macro + 4 small

cells

Macro + 8 small

cells

Macro + 16 small Macro + 32 small

cells cells


Scaling of Capacity: Macro

Cell with D2D D Links

Macro-

D2D

D2D

CoMP

Can combine CoMP with D2D ~ Capacity scalable

system

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential


Scaling of Capacity: D2D D and

Cooperative MIMO without Network

Infrastructure

Cooperated Receive

G

Distributed

MIMO

J

F

H

Cooperated Transmission

Capacity scales with the number of nodes

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential


B4G

• The roll-out out of 4G will address many issues

• Yet 4G is still insufficient to meet anticipated

acceleration in traffic demands

– 1000x increase by 2020 (Significant challenge)

• Described some potential solutions

68


Now let’s take a step

backward and try to put

everything into perspective

69


Wireless Future

Various

Info/Media

Medical

applications

Next

generation

phones

Distributed

Environmental

& Bio Sensing

Security

New Mobile

Devices

Smart RFID

People to People People to machines Machines to Machines

Tomorrow

Trillions of Wireless devices

70


Towards a Dense Ubiquitous

World

PDA

PC

TV

Human-to-Machine

Communication

Vehicle

Home Appliances

RFID tag

Sensors

Camera

Human-to-Human

Communication

NGN

Database,

Web,

application

server

Machine-to-Machine

Communication

Wearable PC

Home server,

gateway

Mobile

Phone

Human-to-Object

Communication

Smart

Card

Telematics,

Navigation

Device

Medical

Device

Humans with

Attached

Devices

Ubiquitous Networking

Objects (Remote Monitoring

and Information Devices)

71

71


Towards Dense Wireless World with High

Demands

72

٧٢

INTERNET OF THINGS

“We are heading into a new era of

ubiquity, where the users of the Internet

will be counted in trillions, and where

humans may become the minority as

generators and receivers of traffic.

Changes brought about by the Internet

will be dwarfed by those prompted by

the networking of everyday objects “ –

UN report

72


What is Internet of Things?

A self-configuring network whose purpose is to connect all things.

Things should have naming, sensing and processing abilities

73


Internet of Things

74


Internet of Things

ITU: ITU Internet Reports

2005

MIT: Auto-ID-Center

1999

IBM: Smart Planet, Winning in China

2009

Obama: Business Round Table

IBM: Smart Planet

2008

2009

Wen Jiabao: Sensing China

2009

75


Internet of Things

Every object can

be addressed

Every object can

communicate

Every object can

be controlled

76


IoT Challenges

• Mass data

– Managing the large amounts of data

• Management

– Designing system from autonomous (independent)

and smart operation

• Security

– Establishing a series of mechanism to protect the

security and privacy needs

• Mobility, Scalability, Infrastructure, ...

77


IoT Challenges

• Energy: Harvesting, conservation & consumption

– New and more efficient and compact energy storage

• Batteries, fuel cells, and printed/polymer batteries, supercapacitors, …

• New energy generation devices coupling energy transmission methods or

energy harvesting/scavenging using energy conversion

• Ultra low power design: from processors/microcontrollers cores, signal

processing & sensors to base stations

• Communications: Physical layer transmission & Protocols

• New, smart multi frequency band, reconfigurable antennas, integrated onchip

solutions

• Modulation schemes and transmission speed allowing multi-frequency

energy efficient communication protocols and transmission rates

• New methods of power consumption management

power consumption management: from network

routing down to the architecture of individual devices.

78


Conclusion

Past (2G) Present (3G/4G) Future

Mobile

Communications

Wireless

Internet

Autonomous

Communications

Cognitive

Wireless World

People-to-People

People-to

to-Machine

Autonomous Machine to Machine

Telemedicine

WIRELESS EVERYWHEREWireless

Active Smart Sensor

Body Network

& Control HomeNetwork

Game Music

Mobile Services

Reconfigurable, Bio Sensor Agile

Interactive TV

Video Conference

Environmental Aware

A New Wireless World of Cognitive and Agile Networks

WiFi

Sensor

IP-TV DMB

Anything Anybody Anywhere Anyhow Anytime

Consumer Much Personal More Electronics Communications

Research for many years to come

Distributed Environmental

& Bio Sensing

79


80

80

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