A. PaulrajStanford University

&Iospan Wireless

Broadband Wireless The MIMO Advantage

Wireless Internet and Mobile ComputingSNRC/Accel Symposium

Stanford UniversityMay 16, 2001

2

WirelessWireless

Subscriber Growth20

000

1995 2005

Su

bsc

rib

ers

in M

illi

ons

20101985

1000

InternetInternet

Source ITU, Merrill Lynch

3

Price / Performance in 5 Years

0

20

40

60

80

100

120

Silicon Storage Fiber Wireless

Price / Performance Growth P

/P G

row

th in

5 y

ears

2

Moore’s Law

4

Limits to Growth ?

0.0001

0.001

0.01

0.1

1

Silicon Mag. Storage Fiber Wireless

Fundamental / Device / Material Limits

Radio 1 ~ 3 Ghz

Today

Source IEEE Proc.

5

• Anytime and anywhere connectivity to high quality and high speed multimedia services to support operations at office and home, and to access entertainment, learning, health care, financial, .. services

• Single device, uniform, personalized, secure, seamless and portable service

Broadband Vision

6

Traffic: Asynchronous/ Isochronous, average loading (6-10%), low or no error tolerance

• User Metric: Time (delay) to down load large files, probability of delay exceeding x2 target

• Carrier metrics – Capacity: Number of users per cell (with target download

rates) for x MHz spectrum allocation or (BPS* / Hz )/ Cell

– Coverage Metric: (BPS* /Hz) x Cell Area

Broadband Wireless - Metrics

7

Principal Challenges in Wireless

High Quality

Seamless High Speed

Low Power

8

Fading Co-channel IntfPath Loss

Bursty Traffic Variable channel

TCP Behavior

Mixed QoS

Impairments / Constraints

Application Constraints

9

Channel Impairments

-15

-10

-5

0

5

10

1

1 1

2 2

2

3 3

-15

-10

-5

0

5

10

CI

Fading Co-Channel Intf.

10

• Deploy more bandwidth, but – Increases spectrum $– Reduces cell size, increases infrastructure $– Forces cell splitting, increases infrastructure $

$

Speed

Challenge of Speed

~ Speed 1.5

11

• Add margin for signal fading ( into noise and co-channel interference)

• Reduces cell size, increases infrastructure $– Reduces reuse (= cell capacity), increases

infrastructure $

Link Quality (1 - Outage)

$

Challenge of Quality

~ Quality 2

12Load /Square Mile

$

Speed and Quality increases $$

Technology ?

Infrastructure Cost

13

What is MIMO Wireless ?

Tx

Rx

Diversity: Increased Diversity

Spatial Multiplexing: Increased rate

Tx

Rx

14

SISO 1SISO 111

Tx Rx

MIMO 2MIMO 222

Tx RRx

MIMO Leverage in Diversity

Reduces Fading Dramatically

15

Range

Sig

nal

/Noi

se

Noise Floor

SISO

MIMO

Diversity Enables Better Coverage

16

Sig

nal

/ In

tf. R

atio

ReuseWeak

MIMOInterference

Aggressive

SISO

Diversity Enables Better Reuse

17

Spatial Multiplexing Increases Speed

SINR

BP

S/H

z

10 dB 20 dB

0

30

4x4

1x1

18

0

0.5

1

1.5

2

2.5

3

3.5

4

Cap

acit

y G

ain

TCM Turbo CDMA* MIMO

* Over TDMA in Mul Access Networks

Past and Present Supernovae ?

SNR Set Point 8 dB

4x4

19

MIMO Advantage

Coverage

Capacity

Number of Antennas N

Co

vera

ge

Cap

acit

y

2 3 4 5

High PowerNetworks

Low PowerNetworks

20

4

Data Rate

0.2 2 20 200

MBPS

Cel

l Siz

eM

acro

Airburst (MIMO OFDM)

Hyperlan802.11a

WCDMA

Loc

Mic

roBroadband Access Standards

4G ?

Hyperaccess

802.16

MIMOMIMO

MIM

OM

IMO

(MIMO OFDM)

21

• Developed by Iospan Wireless for fixed, large cell, broadband access

• PHY based on MIMO-OFDM• MAC with packet reservation and advanced

scheduling • Very high coverage and spectrum efficiency• IPR Licensed from Stanford University

Airburst TM - The MIMO Pioneer

MODEM H/W MAC H/W

MODEM H/W Driver

SF Signaling Scheduler Utilities ARQ LIM

MAC API

Publish and Subscribe

Conn. Mgr.NAU

Control(Future)

Configuration Mgmt.

(Future)Stats

Collection

Fault Mgmt.

SAR Driver (BTS) MAC Driver

22

• High speed and high quality broadband wireless is an emerging opportunity

• MIMO technology now widely recognized as a fundamental leverage for improving price/performance

• Iospan Wireless has developed core air interface technology for large cell fixed access applications

Summary