GCOE Workshop on Advanced Wireless Signal Processing and Networking TechnologyTohoku University, 20-21 Aug. 2008

Opening Remarksp g

Fumiyuki Adachi

Wireless Signal Processing & Networking (WSP&N) LabWireless Signal Processing & Networking (WSP&N) Lab.Dept. of Electrical and Communications Engineering,

Tohoku University, JapanE mail: adachi@ecei tohoku ac jpE-mail: adachi@ecei.tohoku.ac.jp

http://www.mobile.ecei.tohoku.ac.jp/

OUTLINEOUTLINEGlobal COE ProgramChallenge for 4G Wireless

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g

5 ea Global COE P og am5-year Global COE ProgramTohoku University has a long history of outstandingTohoku University has a long history of outstandingresearch, e.g., Yagi-Uda antenna and opticalcommunications technology.Based on our strong background of research and education,our group was selected 5 years ago as COE of its firstphase (April 2002~March 2007)phase (April 2002~March 2007).Now, we started COE program (global COE) called “Centerof Education and Research for Information Electronicsof Education and Research for Information ElectronicsSystems” (April 2007~March 2012).

Program director

&research Research Research

group leader ν-QI school

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group leader

group leader Prof. K. Edamatsu

group leader Prof. M. Kameyama

ν QI schoolleader

Prof. M. KawamataProf. F. Adachi

Ed ti & R hEducation and research are equally important.

Education & Researchq y p

Education in ν-QI school (Quadruple I: School of Interdisciplinary,International, Industry-academic Interchanges)Intensive NT/IT research/

NT/IT Education & Research Center

ResearchEducation

NT/ITν-Q I School

RankedResearch

IntelligentInformation

RAGroup

NetworkSuper

Grants

Student-Organized

International

Information/Device/

Fundamentals

Systemsp

Research

pInternshipsInternational

Conferences

World-Class ResearchFostering World-Class

Young Researchers

Fundamentals

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Long history of original research on information electronicsand strong collaborative education by 3 departments

Focus on systems research3 research groups

(C) IntelligentInformation g p

(23 members)Focus on research into optical and (B) Network

(7)

Systems (4)

wireless networking technology(A) Information

D i

(7)

Devices/Fundamentals

(12)

Invite overseas researchers to int.

Workshops/seminars

symposiaHold small-scale workshops/seminars Int.

ll b tiI t

/seminars

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for deeper discussions

collaboration Miniconferences

Int.symposia

Groups A~C will work in close cooperation to develop thep p pfundamental technologies necessary for human-oriented globalnetworks.

ITClose Close Close cooperation among three groups

Close cooperation among three groupsg pFundamental/practical lectures for

g pFundamental/practical lectures for PhD studentsBroad knowledge and

PhD studentsBroad knowledge and

NT

outlookoutlook

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Wireless

Group A (led by Prof. Keiichi Edamatsu) developsSemiconductors, storage, optical and display devices with super high

G L dperformance (i.e., high density, high speed, high functionality, low powerconsumption, etc.)The fundamentals of information communication devices and theories behind theinformation systems to be used in 10 years time

Prof. Kunio SawayaGroup Leader

Prof. Fumiyuki Adachi

information systems to be used in 10 years time.

Group B (led by Prof. Fumiyuki Adachi) developsSuper-high-speed coherent optical communication technologySuper-high-speed coherent optical communication technology,broadband wireless signal processing technology, secure networkarchitectures, and communications protocols, as well as optical andwireless technologies and distributed networks.

The target data rate of optical communications is 1~10 Tbps usingoptical TDM/WDM technology and the wireless data rate should be asoptical TDM/WDM technology and the wireless data rate should be ashigh as 100 M~1 Gbps over a hostile wireless propagation channel.

Group C (led by Prof. Michitaka Kameyama) develops

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Intelligent communications technology with a more than tenfold improvement inrecognition capability and performanceIntelligent information systems with autonomous recognition and prediction ofthe environment

Ch ll f 4GChallenge for 4GEvery one wants to communicate instantly with anyone, any time,y y y , y ,from anywhere

Arrival of ubiquitous society: communication is available everywhereThis is only possible by wireless Wireless is indispensable in ourThis is only possible by wireless. Wireless is indispensable in ourforthcoming ubiquitous society

Every 10 years, a new wireless technology has come up andh d ichanged our society

1980’s: from “point-to-point” to “anytime, anywhere”communicationcommunication

1G systems (analog)

1990’s: from voice to “narrowband data + voice”2G systems (digital)Access to the Internet

2000’s: “wideband data + voice”2000 s: wideband data + voice3G systems and then 3.5G systems (high speed packet)

2010’s: “broadband data + voice”4G systemsRoaming across heterogeneous networks

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3 5G d 3 9G (LTE) S t3.5G and 3.9G (LTE) Systems3G systems will continue to evolve to meet the3G systems will continue to evolve to meet thedemands of (internet-related) broadband wirelessservices and substantially strengthen its downlinkservices and substantially strengthen its downlinkdata rate capability.

High-speed downlink packet access (HSDPA), calledHigh speed downlink packet access (HSDPA), called3.5G systems of ~14Mbps/5MHz, started in Japan in2006.Even 3.5G of ~14Mbps will sooner or later becomeinsufficient.A 3 9G will appear to provide broadband services ofA 3.9G will appear to provide broadband services of50~100Mbps/20MHz using the 3G bands.

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E l ti I t 4GEvolution Into 4G4G systems are required to provide much faster services of4G systems are required to provide much faster services ofa peak data rate of 100M~1Gbps.ITU allocated the spectrum for 4G systems in Dec. 2007.

450~470MHz (20MHz), 790~806MHz (16MHz), 2.3~2.4GMHz(100MHz), 3.4G~3.6GHz Global use (200MHz)

a

4Gpointto

NarrowbandEra

WidebandEra

BroadbandEra

2G~64kbps

1G~2.4kbps

ype

tim

edi 3G

~2Mbps

4G100M~1Gbps

0G

-to-point

50~100Mbps

Broadbandwirelessrv

ice

t

Mul t ~14MbpsVoice only

3G LTE

Ser

Voic

e IMT-2000

HSDPA

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1980 1990 2000 Year

V

2010We are here

T h i l I f 4GTechnical Issues for 4GFor a peak data rate of ~1Gbps/BS, there are twoFor a peak data rate of 1Gbps/BS, there are twoimportant technical issues to address.Spectrum efficiency

The available bandwidth in the global frequency band is200MHz only. This must be shared by several operators.1Gbps/100MHz is equivalent to >10bps/Hz/BS1Gbps/100MHz is equivalent to >10bps/Hz/BS.This target must be achieved in an extremely frequency-selective wireless channel, where strong inter-symboli t f (ISI) i d d S d d li tiinterference (ISI) is produced. Some advanced equalizationtechnique is necessary.

Transmit powerTransmit powerPeak power is in proportion to “transmission rate”.For a very high rate transmission, a prohibitively high transmitpower is required if the same communication range in distanceis kept as in the present cellular systems.To keep the transmit power the same as in the presentTo keep the transmit power the same as in the presentsystems, fundamental change is necessary in wireless accessnetwork.

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S t Effi i P blSpectrum Efficiency ProblemIn terrestrial wireless communications, the transmitted,signal is reflected or diffracted by large buildings betweentransmitter and receiver, creating propagation paths havingdifferent time delaysdifferent time delays.For 1Gbps transmission, 1bit time length is equivalent tothe distance of 0.3 m. So, many distinct multipaths exist,th b t l h i th h l fthereby extremely enhancing the channel frequency-selectivity.

Large obstaclesd-4

LocalTransmitter Localscatterers

Transmitter

ReceiverReflection/

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diffraction

The transfer function The transfer function of wireless channel is no longer constant

th i l1

10

l gai

n

over the signalbandwidth.Challenge is to

0.1Cha

nnel

Challenge is to transmit broadband data close to 1 Gbps

ith hi h lit

0.010 10 20 30 40 50 60 70 80 90 100

Frequency (MHz)with high quality over such a severe frequency-selective

10

Frequency (MHz)

nfrequency selective channel.Giga-bit wireless

1

hann

el g

ain

technology of >10bps/Hz/BS is necessary for 4G

0.1Ch

L=16 Uniform power delay profilel-th path time delay=100l + [-50,50)ns

necessary for 4G.

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0.010 1 2 3 4 5 6 7 8 9 10

Frequency (MHz)

H T A hi 1Gb ?How To Achieve 1Gbps?What is Giga-bit wireless technology for 4G?What is Giga bit wireless technology for 4G?

Multi-access, HARQ, modulation,MIMO, access network, …..

In 3.9G or 3G LTE, wireless downlink access will be basedon multi-carrier technique, e.g. OFDMA, while uplink accessbased on single carrier technique with FDEbased on single-carrier technique with FDE.

FDMAency

Frequency-domain Signal ProcessingTime-domain Signal

?f3f2f1Fr

eque

OFDMA SC-FDMA

gProcessing

3 9G

4G ?Time1G CDMA

# 3Si l i

OFDMA，SC FDMA3.9G

TDMA

Freq

.

1 3 12 2 3 Freq

. # 2# 3

Spreadingd #1

3G

Single-carrierCode-domain

FA/Tohoku University 1308/20/2008 FA/Tohoku University 13Time

F

2G

code#1

Time

T it P P blTransmit Power ProblemData transmission of 100Mbps~1Gbps requires aData transmission of 100Mbps 1Gbps requires aprohibitively high transmit power

Peak power is in proportion to “transmission rate” x “fc2.6Peak power is in proportion to transmission rate x fc[Hata-formula]” where fc is the carrier frequency.Assume that the required transmit power for 8kbps@2GHz is1Watt for a communication range of 1 000m1Watt for a communication range of 1,000m.The required peak transmission power for 1Gbps@3.5GHzneeds to be increased by 1Gbps/8kbps x (3.5GHz/2GHz)2.6 =y p p ( )535,561 times, that is, 536kWatt. Obviously, this cannot beallowed.

T k th 1W th i tiTo keep the 1W power, the communication rangeshould be reduced by 43 times(i.e., 1,000m

23m)23m)

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* M. Hata, “Empirical formula for propagation loss inland mobile radio services”, IEEE Trans. Veh.Technol., VT-29, pp. 317-325, 1980.

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Frequency-domain E li ti (FDE)Equalization (FDE)

1G, 2G and 3G used Spreading 1G, 2G and 3G used FDMA，TDMA，and DS-CDMA,

ti l All f

Spreading code

+GIS/P IFFT P/S

MC-CDMA, OFDMData Modulatedsequence

Transmitsignal

respectively. All of them are based on time-domain signal

+GIS/P IFFT P/S

DS-CDMA(a) Transmittertime domain signal processingWhat signal

i h ld b

Spreading code

Σ

MC-CDMA, OFDMDespreading

processing should be used for 4G? DS-CDMA with FDE can

-GI S/P FFT P/SFDE ΣSoft decision

data sequenceReceived

signalCDMA with FDE can remain as an important multiple

t h i f

IFFT DS-CDMA

q

(b) Receiver

access technique for 4G wireless. Transmitter/receiver structure

(DS- and MC-CDMA, OFDM)

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* F. Adachi, D. Garg, S. Takaoka, and K. Takeda, “BroadbandCDMA techniques,” IEEE Wireless CommunicationsMagazine, Vol. 12, No. 2, pp.8-18, Apr. 2005.

H T A hi 1Gb ?How To Achieve 1Gbps?4G target of peak data rate is ~1Gbps, but the available4G target of peak data rate is 1Gbps, but the availablebandwidth may be 100MHz in 4G (3.4~3.6GHz band).1Gbps/100MHz/BS=10bps/Hz/BS

If we want to achieve this goal by multi-level modulation, 1024QAM isrequired.However, the achievable BER performance severely degrades., p y g

16QAM4QAM(2b /H )

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16QAM(4bps/Hz)(2bps/Hz)

1024QAM(10bps/Hz)

MIMO Multiplexing May Be A S iSavior

Increasing the no 80Increasing the no. of antennas can improve the

70

80

8

NxN MIMO (w/receive diversity)

improve the spectrum efficiency or can decrease the 50

60

6

7

8

o a d arequired transmit power.

40

C(b

ps/H

z)

5

4

6

5

p

20

30C 4

3

2

10

2

N=1

00 10 20 30

Average total received Es/N0 per receive antenna (dB)

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G. J. Foschini and M. J. Gans, “On limits of wirelesscommunications in a fading environment when using multipleantennas,” Wireless Personal Commun., Vol.6, No. 3, pp.311-335, Mar. 1998.

However, MIMO Cannot Solve P P blPower Problem

Links for broadband data services are severely power-Links for broadband data services are severely powerlimited.

Peak power is in proportion to “transmission rate” x “fc2.6

[H t f l ]” h f i th i f[Hata-formula]” where fc is the carrier frequency.Let’s consider the peak transmit power for 1Gbps@3.5GHz ata communication range of 1,000m. We assume the requireda co u cat o a ge o ,000 e assu e t e equ edtransmit power for 8kbps@2GHz is 1Watt.The required peak transmission power is

b /8kb ( / )2 6 h1Gbps/8kbps x (3.5GHz/2GHz)2.6 = 535,561 times, that is536kWatt. Obviously, this cannot be allowed.To keep the transmission power at 1Watt level, theTo keep the transmission power at 1Watt level, thecommunication range should be reduced by about 43.3 times(e.g., 1,000m 23m cell) if the propagation path lossexponent is 3 5exponent is 3.5.

Fundamental change is necessary in wireless accessnetwork Present cellular architecture may not work.

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y

FA/Tohoku University 18

M. Hata, “Empirical formula for propagation loss in land mobile radio services”, IEEE Trans. Veh. Technol., VT-29, pp. 317-325, 1980. 08/20/2008

Multi hop Relay TechniqueMulti-hop Relay TechniquePromising technique is multihop relay.Promising technique is multihop relay.Transmit power of mobile terminal, as well as the totaltransmit power, can be reduced significantly by applyingmulti-hop relay technique.

exponent.losspath thedenotes)5.3( where, 1

≈α∝ αRPh

R

Single-hop

Base stationMulti-hopMobile terminal

1since

hops. ofnumber thedenotes where, )/(1

1

<<

⋅=⋅∝α−

α−αα

JPP

JJRJRJPtotal

totalmh

2008/06/23 FA/Tohoku University 19

1.since 1 << JPP hmh

Programg20 August (Wednesday, Katahira Campus)

13:30~14:00 Opening Remarks,p g ,Fumiyuki Adachi, Tohoku University, Japan

14:00~14:50 "Recent advances in frequency domain equalization",Prof. David Falconer, Carleton University, Canada

14:50~15:10 Coffee break15:10~16:00 "Capacity bounds and signaling schemes for bi15:10~16:00 Capacity bounds and signaling schemes for bi-

directional coded cooperation protocols",Prof. Vahid Tarokh, Harvard University, USA

16:00~16:50 "Evolving 4G (WIMAX and LTE) to the next level",Prof. Arogyaswami Paulraj, Stanford University, USA

" d h f d d"16:50~17:40 "Radio Access Techniques for LTE-Advanced",Prof. Mamoru Sawahashi, Musashi Institute ofTechnology, JapanTechnology, Japan

17:40~18:00 Break18:00~20:00 Welcome Reception

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Programg21 August (Thursday, Aobayama Campus)(a part of IEEE VTS APWCS)(a part of IEEE VTS APWCS)

9:15~ 9:25 Opening Session (APWCS)9:25~10:10 "Review of research and development onp

antennas in Tohoku University",Prof. Kunio Sawaya, Tohoku University, Japan

10:10~10:30 Coffee break10:30~11:15 "MIMO signal processing and the impact of

ti l t ff t "practical antenna effects",Prof. Ross Murch, Hong Kong University ofScience and Technology ChinaScience and Technology, China

11:15~12:00 "Lattice reduction based MIMO detection andits application to multiuser systems",pp y ,Prof. Jinho Choi, University of Swansea, UK

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S C l di R kSome Concluding RemarksNext generation wireless networks will require Giga-bitNext generation wireless networks will require Giga bitwireless technology of ~1Gbps and >10bps/Hz/BS undersevere co-channel interference.Lots of interesting and important research topics remainbefore the born of next generation wireless systems.Some of the important wireless techniques will beSome of the important wireless techniques will bepresented in this GCOE workshop.

Please enjoy the GCOE workshop!Please enjoy the GCOE workshop!

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