Marconi/WINLAB celebration, Sept. 30, 1999 Day/Adachi.pdf · 1G 2G 3G Narrowband Era Wideband Era Service type ... subtraction is performed successively for different users in

NTT DoCoMo/FA/99.9.30 1

Challenges of Wireless Communications

Fumiyuki AdachiWireless Laboratories

NTT Mobile Communications Network, Inc. e-mail: [email protected]

1. Bridging the Expanse of Mobile MultimediaOutline

2. Trends in Wireless Access Technology

4. Beyond Global 3G3. Global 3G CDMA

Marconi/WINLAB celebration, Sept. 30, 1999


Growth of Mobile Communications in Japan

July 1995Start of PHS

20,9

m

5.98

m

Dec. 199844,990,000(35.5%)

39.0

m

7 m

28.7

m

Dec. 199735,739,000

Aug. 199951,262,000 (40.5%)

5.698m45.564m

Mar. 1993PDC

PHSCellular

199819880

5

10

15

20

25

30

35

1989 1990 1991 1992 1993 1994 1995 1996 1997

40Million

Num

ber

of u

sers

Year

nPenetration rate of mobile communications surpassed 40% point and is expected to overtake fixed telephone within a year nNumber of fixed telephone lines has declined to 58million (its

peak was 61 million in 1997)


Weight and Talk Time of Mobile Phones

Source: K. Honma et al., “Mobile terminal technologies,” Proc. IEICE, Feb. 1999

24003000

900

22575

0

1000

2000

3000

1979 1985 1987 1993 1997

Shou

lder

-typ

e

Veh

icle

-mou

nted

Wei

ght (

g)

(a) Mobile phone weight

PDCAnalog

Year

Tal

k tim

e (m

in)

4060 60

220

0

50

100

150

200

250

1979 1985 1987 1993 1997

(b) Talk timeYear

nIncreased utilization efficiency of portable phones is an important factor of gaining popularity of mobile phones


Time Taken to arrive at 10% (house hold) Point

Source: Communications White Paper, MPT, 1999

5

13

15

19

76

0 20 40 60 80Year

InternetPersonal computer

Mobile commun.

Fax

Telephone

nThe rate at which mobile radio and Internet communications services have proliferated throughout our society is strikingnIn the fixed networks, voice conversation was a long-time

dominant service, but the introduction of Internet communication services is significantly changing our society


Evolution to Wireless Multimedia Society

Computer Internet

MobileCommunications

nA combination of mobile communications, personal computers, and Internet services will drive our society to evolve into a wireless multimedia society nUltimate goal is to communicate any information with

anyone, at any time, from anywherenRecently, mobile communications services are shifting

their focus from only voice conversation to Internet connections in line with the increasing popularity of Internet communications in fixed networks


Multimedia-type “i-mode service”Over PDC-Packet Networks

PDC-PNetworkInternet

IP

IP

Server

TCP/IPHTTP

IPLeased line

PDC-P: PDC Packet (9.6kbps)IP: Information Provider

PDC/PDC-P

PDC Network

Voi

ce

nThe first step toward bridging the expanse from today’s society to wireless multimedia society is seen in a new Internet access service called “i-mode service”


Contents of “i-mode service”

Voice

E-m

ailin

g

Web

acc

ess

TransactionsnMobile bankingnReservations for

flights,accommo-dationsnStock tradingetc.

Daily informationnWeathernNewsnTown info.nStock pricesetc.

Data basenRestaurant guide nTown pagenDictionarynTrain transfer info.nCooking recipesetc.

EntertainmentnKaraokenNetwork gamenMovie listingsnFortune-telling etc.

n“i-mode service” provides e-mailing, web access, various types of on-line services as well as voice conversation


Rapid Growth of “i-mode service”

0

200

400

600

800

1000

Feb.99 Apr. June 8 Aug.(a) Number of users (x1000)

0

200

400

600

800

1000

1200

1400

Apr. May June July 8 Aug.(b) Number of IP sites

n Rapid growth: one million users in Aug. 1999 after its introduction in Feb. 1999

n Accelerating the popularity of “i-mode services” is the increasing number of IP sites (positive feedback): over 1400 in 8 Aug.


Preparing for Wireless Multimedia Society

Increased capacity(consistent growth of markets)

3G System(IMT-2000)

Multimedia services(Internet/ISDN)

Global standard(worldwide travelers,

economy of global scale)

nMajor services will shift from voice to multimedia services over Internet indicated by “i-mode”, but with much faster transfer rate and much better representationnFixed networks Internet traffic will exceed voice traffic in

2001 and 22% of mobile users will use multimedia services in 2000


IMT-2000 Deployment and Capability

Pedestrian384kbps

Vehicular144kbps

IMT-2000Network

Indoor2000Mbps

n It is expected to be deployed worldwide starting around 2001-2002

n Technical target: information rates of up to 2 Mbps, same quality as fixed networks, use of 2-GHz bands

n “IMT-2000” probably better represents “Internet Mobile Telecommunications in the years of 2000’s


Evolution Path to Wireless Multimedia Society

Analog

AMPS

TACSNTTkbps4.2~

Digital

IS95IS136GSMPDC

kbps64~

IMT-2000(Internet Mobile

Telecommunications)

kbps2000~

1980 1990 2000 Year

3G2G1GNarrowband Era Wideband Era

Serv

ice

type

Voi

ceM

ulti

med

ianTo realize IMT-2000, a new wideband wireless access

technique incorporating as many recent technological achievements as possible is necessary


Harmonization Solution to Global 3Gn8 out of 10 proposals submitted to the ITU in July 1998 were

based on DS-CDMAüTIA: cdma2000 üJapan:ARIB started its selection process for a wireless access

technique in 1995 and chose W-CDMA in 1997üETSI: UTRA (W-CDMA for FDD and TD/CDMA for TDD)

nIntensive harmonization studies are currently under way to establish a global 3G standard

Direct Spread3.84Mcps

G3G CDMA

Multi-carrier3.68Mcps

TDD

FDDEvolved GSM

Evolved ANSI-41

Core Network

NNI


R&D Plan for IMT-2000

1996 1997 1998 199919951994 2000 2001

Commercialsystem developmentphase

Research phase (transmission up to2Mbps, voice/video)

System-test

phase

Field test 2

W-CDMAair interface

Revised W-CDMA Interference canceller, Adaptive antenna array

Design &Implementation

Field test 1

Design/ manufacture Field test

W-CDMA air interface Control functions (L2/L3)RFP

RFC

nTarget year of commercial deployment is Mar. 2001


TokyoTokyo

YRPYRP

4 sites

3 sites

Akasaka, Aoyama, Mita, Chiyoda

System Test


Migration Path Toward IMT-2000

IMT-2000RAN

IMT-2000 CN

IMT-2000terminal

Mobility Management: GSM evolved MAP

Service Control: INAP (CAMEL)

GSM evolved RAN-CN I/F

W-CDMA

n Service area of IMT-2000 system (IMT-2000 RAN+IMT-2000 CN) will be overlayed with that of existing PDC system (PDC RAN+ PDC CN).

PDC/IMT-2000

dual modedual band

n Initially, IMT2000-PDC dual mode terminal as well as IMT-2000 single mode terminal will be introduced .

n Overlay of IMT-2000 with PDC

PDC CNPDC

(Proprietary)PDC-TDMA PDC RAN

GSM evolved NNI

IWF

n IMT-2000 CN connects and inter-works with PDC through IWF (inter-working function).


Advanced Transceivers

q In a multimedia W-CDMA communications system, link capacity is predominantly limited by high rate users producing severe multi-access interference (MAI)

- Interference canceling (IC) receiverMulti-stage successive IC receiver: Interference subtraction is performed successively for different users in the order of decreasing power, thereby improving SIR for low rate users

q Two promising advanced receivers

- Adaptive antenna array receive/transmit diversityBeam is directed toward the desired user while reducing interference particularly from high rate users


Multi-stage IC Receiver Structureq Interference subtraction is performed successively for

different users in the order of decreasing power

1st stage 2nd stage

User #1

User #K

User #2

Receivedsignal

Channelranking to next stage

Ranking information

DCEIGU

++-

DCEIGU

++-

DCEIGU

++-

DCEIGU

-

+

DCEIGU

-

+

+

++

++

++

DCEIGU

-+

+

++

+ -

r(t) User#1data

User#2data

User#Kdata

stageth -jeach for 1-K 2,.., l, 0,k =

r(t) +

CEIGUuser #k

D +

D

(j)kr

(j)1-kr

(j)ks

+ -

++

1)-(jks

0s(-1)k =

0k and0j iif=

=

Iterative multi-stage IC receiver

CEIGU: channel estimation and interference replica generation unit


Measured BER Performance with 3-stage IC (Laboratory Experiment)

q The BER performance improvement is almost saturated at 3-stage

1.024Mc/s, SF=162-path Rayleigh, fDTslot=0.05 (80Hz)Antenna diversity, Convolutional codingNo fast TPC

K 3,..., 2,kfor /NE/NE 01 b,0k b,

==

0 5 10 15 2010 -5

10 -4

10 -3

10 -2

10 -1

10 0

Ave

rage

BE

R

Average Eb/N0 per antenna (dB)

Singleuser

K=16

K=13

K=9

K=5

MF3-stageMulti-stage IC


Broadband Wireless Communications1G

100M

10M

1M

100K

10K

Dat

a ra

te

Indoor Outdoor

WirelessLAN

Stationary Quasi-stationary

Quasi-stationary Pedestrian Vehicular

Mobility

IMT-2000(3G W-CDMA)

Cordless

High-speedwireless

LAN

PHS

2G cellular (PDC)

4G broadband wirelesscommun . network


What is 4G System?

nA major objective is to offer mobile users broadband multimedia services, which will soon be in full force in fixed networks based on next generation Internet technologynInformation transferred over the Internet will become

increasingly rich, most of the information may contain high-quality still and moving imagesnOther services may include Various e-commerce transactions Broadcasting services Support of Intelligent Transportation Systems (ITS)


4G System Is A Broadband Wireless Packet System?

n Broadband wireless multiple access optimized for IP transfer

ü Broadband packet access with peak rate of more than 2Mbps in a vehicular environment and 10-20Mbps in stationary-to-pedestrian environments

ü Flexible resource allocation between up- and down-linkn Wireless IP networkü Intelligent IP data routing algorithm with mobility

handlingü Pico-cell with fast handoff algorithmn Inter-operation with 3Gü Software radio technology


Technical Challenges

Asymmetric linkq Access to NASA Web site to retrieve a galaxy image of

259kBq Amount of data transmitted

Up-link: 5kB Down-link: 274MB

q Time=4min 15sec for PDC (8.6kbps throughput)

q Broadband propagation channel produces severer frequency selective fading- Robust broadband data modulation scheme is necessary

q Significant difference between forward and reverse link ratese.g. WEB site access and down load of a 259kB image data indicates up/down link rate ratio of 1:55

q Which wireless access, TDMA, DS-CDMA, or OFDM?üIt may be hybrid use of OFDM and DS-CDMA with TDD


Technical Challenges (cont’d)q Power limitation

RatefPower 2.6 ×∝

q Power reduction and interference suppression techniques are important- Space-time processing (adaptive antenna array and coding)- Adaptive modulation- Packet interference cancellation

- Example:Transmit power with 64 kbps at 5GHz is 87 times larger than with 8kbps at 2GHz, or cell size must be reduced by about 3.7 times (pico cell)


Concept of 4G System

3G network

4G 4G

q 4G island covers high multimedia traffic area q 4G island inter-operates with 3G networkq Flexible extension of 4G island

1-2km

10-100m

Satellite cell

4G island(clustered cell area)

Array beam feeder

Switching center


Conclusionq G3G CDMA system

- Target year is 2001- Flexible offer of wideband multimedia services in addition to

basic service (voice/fax/voice-band data)- Up to 2Mbps transfer rates- Larger capacity and wider coverage than any other 2nd

generation systems (GSM, PDC, IS95, etc)

- Adaptive antenna array transceiver- Interference canceling receiver

q G3G CDMA can be enhanced by advanced wireless techniques, i.e.

- Target year is around 2010- Broadband wireless packet access with peak rate of > 20Mbps- Significantly bandwidt/power efficient techniques necessary

Space-time processing, packet interference cancellation- Inter-operation with 3G

Software radio technology

q 4G system for rich multimedia communications services


We will continuously face very difficult but

interesting technical challenges in the coming

years!Thank you!

Documents

Marconi/WINLAB celebration, Sept. 30, 1999 Day/Adachi.pdf · 1G 2G 3G Narrowband Era Wideband Era Service type ... subtraction is performed successively for different users in