crime and punishment for cognitive radiossahai/presentations/...outline motivation crime and...

Crime and Punishment for Cognitive Radios

Anant Sahaipresenting joint work with:

Kristen Woyach George Atia Venkatesh Saligrama

BWRC and Wireless Foundations CenterU.C. Berkeley

Major support from the National Science Foundation

Allerton Conference

Anant Sahai (UC Berkeley) Crime and Punishment 9/24/2008 1 / 11

Motivation: recovering spectrum holes


Motivation: cooperation


Outline

MotivationCrime and punishment

I Prior work:F Rose, Ulukus, Yates ’01F Popescu and Rose ’04F Etkin and Tse ’05F Huang, Berry, Honig ’04F Xu, Kamat, Trappe ’06

I Single-band modelI Multi-band model

Identity (preview of DySpAN ’08)


Single-band model

False Alarm

Legal TX

SecondaryTX No TX

No Cheat

Cheat

False Alarm

Legal TX

Primary

Cognitive

Jail

Pcatch

Ppen

p1

q1

Ptx = q/(q+p)


Single-band model

00.25

0.50.75

1

00.25

0.50.7510

0.25

0.5

0.75

1

pPtx

Pcheat

Always cheat

Never cheat

Pcatch = 1Ppen = 0.6


Single-band model

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

1

2

3

4

5

6

7

8

9

10

Ppen

β =

pai

n of

jail

Pcatch = 0.1

0.2

0.4

0.60.8

1


Multi-band model

TX No TX

No Cheat

Cheat

False Alarm

Legal TX

q

SecondaryTX No TX

No Cheat

Cheat

False Alarm

Legal TX

Primary

Cognitive

Band 1Band 2

Band 3

Band B

Global Jail

Pcatch

Pcatch

Primary

Ppen

p1

q1

pN

qN

Ptx = q/(q+p)


Multi-band model

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

1

2

3

4

5

6

7

8

9

10

β =

hom

e ba

nds

requ

ired

to in

cent

iviz

e no

che

atin

g

Ppen

B = 1

B = 3

B = 5

B = 7

B = 9

Pcatch = 1


Multi-band model with false convictions

TX No TX

No Cheat

Cheat

False Alarm

Legal TX

q

SecondaryTX No TX

No Cheat

Cheat

False Alarm

Legal TX

Primary

Cognitive

Band 1Band 2

Band 3

Band B

Global Jail

Pcatch

Pcatch

Primary

Pwrong

Pwrong

Ppen

p1

q1

pN

qN

Ptx = q/(q+p)



0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

5

10

15

20

25

30

35

40β

= h

ome

band

s re

quire

d to

ince

ntiv

ize

no c

heat

ing

Pwrong

1

3

5

7

B = 9

Pcatch = 1Ppen = 0.6



0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

5

10

15

20

25

30

35

40β

= h

ome

band

s re

quire

d to

ince

ntiv

ize

no c

heat

ing

Pwrong

Pcatch = 0.1

0.2

0.4

0.6

0.8

1

B = 3Ppen = 0.6



Pcatch = 1Pcatch = 0.5

Pcatch = 0.1Ppe

n

0

1

0.5Pwrong0.1 0.2 0.3 0.4

0.5

B = 3



Pcatch = 1Pcatch = 0.5

Pcatch = 0.1Ppe

n

0

1

0.5Pwrong0.1 0.2 0.3 0.4

0.5

B = 3

Ppe

n

0.5

10

1

01 2 6 84

Expansion

Pcatch = 0.1

Pcatch = 0.5

Pcatch = 1

Pwrong = 0.03


The cognitive user’s perspective

30

1

2

10 20

3

Expansion

0

0

1

0

0.5

Utility

Fraction of time in jail Ptx = 0.55Pcatch = 1

Pwrong = 0.03


The cognitive user’s perspective


The “overhead” needed for bandwidth expansion

Exp

ansi

on

0

40

20

30

10

Overhead0.1 0.2 0.3 0.4 0.5

Pwrong = 0.01

Pwrong = 0.06

Pwrong = 0.1

Pwrong = 0.035

Pwrong = .02

Pwrong = 0.001

MaximalExpansion

Ptx = 0.55Pcatch = 1


The “overhead” needed for bandwidth expansion

0 0.1 0.2 0.3 0.4 0.50

10

20

30

40

Overhead

Expansion

Pcatch = 1

0.8

0.6

0.4

0.2

0.1

Ptx = 0.55Pwrong = 0.02

MaximalExpansion


Outline

Motivation

Crime and punishmentIdentity (preview of DySpAN ’08)

I Prior work:F Faulhaber ’05F Hall, Barbeau, Kranakis ’03F Brik, Banerjee, Gruteser, Oh ’08F Rasmussen and Capkun ’07F Rozovsky and Kumar ’01


Identity through taboos

Network IDUser ID

× Device IDTX Identity: Band 1

TX Identity: Band 2

TX Identity: Band 3

. . .Cannot transmit



1000

800

600

400

200

02000 4000 6000 8000 100000

Time steps until conviction

Per

cent

age

incr

ease

in P

rimar

y er

rors 5% background error in Primary link

Pcatch = 0.9Pwrong = 0.005

Overhead = 5%

Overhead = 10%

Overhead = 25%



Enf

orce

men

t ove

rhea

d

2000 4000 6000 8000 100000

0.1

0.2

0.3

0.4

0.5

0

Time steps until conviction

200% increase in primary errors

100%

50%

65%



Min

imum

enf

orce

men

t ove

rhea

d

Number of users

Catch coalition of 4



0.1

0.2

0.3

0.4

0.5

02 73 65410 1010 101010

Time steps until conviction = 3000


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