CRT CR Practice 2010

7/31/2019 CRT CR Practice 2010

1/15

Practical Considerations forPractical Considerations for

NetworkingEnvironmentsNetworkingEnvironments

James Jody Neelames.nee cr w re ess.com

Cognitive Radio Technologies

147 Mill Ridge Rd, Ste 119

Lynchburg, VA 24502

Web: www.crtwireless.com

Ph: (540) 230-6012

Email: [email protected]


2/15

MaterialMaterial Interactions of CRs

Impact of Hostile Users



Lynchburg, VA 24502


Ph: (540) 230-6012



3/15

Issues Can Occur When MultipleIssues Can Occur When Multiple

Flash Crash of May 6, 2010

Combination of bad economicnews, big bet by Universa, and

interactions of traders and

computers

http://www.legitreviews.com/images/reviews/news/dow_drop.jpg

Housing Bubble Bounce up instead of

Slower interactions leadto slower changes



Lynchburg, VA 24502


Ph: (540) 230-6012


beliefs play in instability3

http://www.nytimes.com/imagepages/20

06/08/26/weekinreview/27leon_graph2.

html


4/15

In heavily loaded networks, a single vacationIn heavily loaded networks, a single vacation

can s awn an infinite ada tation rocesscan s awn an infinite ada tation rocess Suppose

31 21 12 32 23 13

Without loss of generality2

31, 12, 23

g21, g32, g13 = 0.5

4,5,1,3,2,6,4, 13

Chan. (0,0,0) (0,0,1) (0,1,0) (0,1,1) (1,0,0) (1,0,1) (1,1,0) (1,1,1)

Interference Characterization

http://www1.istockphoto.com/file_thumbview_approve/2820949/2/istockphoto_2820949_dect_phone.jpg

Cradle Image:

http://www.skypejournal.com/blog/archives/images/AVM_7170_D.jpg



Lynchburg, VA 24502


Ph: (540) 230-6012


Interf. (1.5,1.5,1.5) (0.5,1,0) (1,0,0.5) (0,0.5,1) (0,0.5,1) (1,0,0.5) (0.5,1,0) (1.5,1.5,1.5)

0 1 2 3 4 5 6 7


5/15

Generalized Insights from theGeneralized Insights from the

If # links / clusters > # channels, decentralized channel choices will

have a non-zero loo in robabilit

As # links / clusters, looping probability goes to 1 Can be mitigated by increasing # of channels (DECT has 120) or

Both waste spectrum

And were talking 100s of ms for vacation times

Rippling in Cisco WiFi Enterprise Networks

www.hubbert.org/labels/Ripple.html

Aug 2009 White Spaces paper from Microsoft

Major reason most routing algorithms are not load sensitive



Lynchburg, VA 24502


Ph: (540) 230-6012



6/15

Potential games yield predictablePotential games yield predictable

interactionsinteractions Existence of a function (called thepotential function, V), that reflectsthe change in utility seen by a

.

Cognitive radio interpretation: Every time a cognitive radio unilaterallyadapts in a way that furthers its own

-,increases.

Our use:

Predictable, stable emergent behavior

will immediately break themonotonicity

V(a)



Lynchburg, VA 24502


Ph: (540) 230-6012



7/15

Example behaviorExample behavior

For example, for a collection of 802.11 clusters

independently choosing operating frequencies

1. All self-interested

adaptations

Clusters

Frequencies

2. Based only on

No synchronization required

Observed

0 5 10 15 20

25-30 dB

performance

No information exchange overhead

Interference

Levels

0 5 10 15 20

3. Decrease aggregatenetwork interference

Aggregate

Network

25-30 dB



Lynchburg, VA 24502


Ph: (540) 230-6012


CRT Proprietary7

Self-stable

Converges to local-optima

Interference

0 5 10 15 20seconds


8/15

No network is an islandNo network is an island Many TVWS standards

Decisions impact one another Etiquette

.

802.16h (CR WiMAX) 802.11af (WhiteFi)

oor na e qu e per o s

Common time base, scheduling Share information

Sensing

Merging?

1900.6 Draft 1



Lynchburg, VA 24502


Ph: (540) 230-6012


. -


9/15

Hostile users can create problemsHostile users can create problems

Suppose another network is

compromised in your areaWhat if theenvironment

Their behavior influences your

networks adaptations

is unstable?

Tone Jamming

(Mobile)Fixed Interferer

(Mobile)

Hopping Jamming

(Mobile)Adaptive Interferer

(Mobile)

Clusters

Stability impact

~30 dBObserved InterferenceLevels

0 5 10 15 20

0 5 10 15 20

Shifted Left

(jammers)

Greater

slope

(mobility

) Smaller to zerogain

Aggregate Network

Interference

0 5 10 15 20seconds



Lynchburg, VA 24502


Ph: (540) 230-6012


CRT Proprietary9

Need to consider external actors Detect unexpected behavior, adjust accordingly


10/15

Hostile users can blend inHostile users can blend in Normal CR

5 malicious, 30 normal

Average interference levels for nodes 6-35

knowledge about network state Maximize system (own)

performance35 dB

Hostile CR

Given available adaptations and

knowledge about network state 35 normal

Minimize system performance Adapt at inopportune times

Simply minimizeperformance

nsure marg na y s a enetwork goes unstable

Plus learning exploits And s oofin



Lynchburg, VA 24502


Ph: (540) 230-6012


And information corruption


11/15

Malicious != SelfishMalicious != Selfish

Popular solution tomischievous nodes(selfish nodes that

damage network) is topunish nodes

brainwash learningnodes

Imperfect information can

From Fig 6 in [MacKenzie_01]

o usca e pun s menfrom mischievousbehavior and producecatastro hic cascades Brittleness

Even with perfectinformation, malicious



Lynchburg, VA 24502


Ph: (540) 230-6012


node may be masochistic rom r vastava_


12/15

Detecting aberrant behavior fromDetecting aberrant behavior from

redictable emer ent ro ertiesredictable emer ent ro erties

100

120

140

el

120

140

Adaptations Adaptations

0 50 100 150 200 250 300

40

60

80

Chann

0 50 100 150 200 250 300

40

60

80

Channel

Policy restricted channels

-60

-50

-40

dBm)-60

-50

Bm)

Radio Utilities

0 50 100 150 200 250 300-90

-80

-70Ii(f)(

0 50 100 150 200 250 300-90

-80

-

Ii(f)(d

-60

-50

-40

-30

(f)(dBm)

-

-60

-55

-50

)(dBm)

Potential Function

Malicious User Detected



Lynchburg, VA 24502


Ph: (540) 230-6012


0 50 100 150 200 250 300

-80

-70

iteration0 50 100 150 200 250 300-75

-70

-

iteration

( o a c ous ser

Potential Function


13/15

Implementation DiscussionImplementation Discussion

Implement as monitoringsystem that evaluatespo en a emergen unc on

Frequently sum ofperformance levels

Complexity is in theransm ss on connec v y

No single node / clusterknows / can evaluateemergent function

V

But a malicious CR will lie E.g., Claim massive gains to

offset others losses

With BSI a malicious node

cant tell a credible lie! Other relationships exist

Need to be WPG / EPG for



Lynchburg, VA 24502


Ph: (540) 230-6012



14/15

Security IssuesSecurity Issues

[Clancy_08]

Primary user emulation attacks

Spectrum sensing data

falsification [Chen_08a]

e e man pu a on a ac s

A cognitive radio virus

_

Replay sensing attacks [Bian_08] False coexistence information

_

Honeypot attacks [Newman_09]

Chaff point attacks [Newman_09]

[Brown_08]

Cognitive Radio Technologies147 Mill Ridge Rd, Ste 119

Lynchburg, VA 24502


Ph: (540) 230-6012



15/15

Questions you should askQuestions you should ask

Can you predict what willhappen when the networkscales and interactions occur?

How might your measures beturned against you? ens ng, earn ng, po cy

enforcement

Even when following the rules

networks other than your own? Can be attacked from outside

without jamming

If there are vulnerabilities, howwill you detect that they arebeing exploited?

Cognitive Radio Technologies147 Mill Ridge Rd, Ste 119

Lynchburg, VA 24502


Ph: (540) 230-6012


Documents

CRT CR Practice 2010