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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]
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MaterialMaterial Interactions of CRs
Impact of Hostile Users
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
beliefs play in instability3
http://www.nytimes.com/imagepages/20
06/08/26/weekinreview/27leon_graph2.
html
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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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)
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
CRT Proprietary7
Self-stable
Converges to local-optima
Interference
0 5 10 15 20seconds
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
. -
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
CRT Proprietary9
Need to consider external actors Detect unexpected behavior, adjust accordingly
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
And information corruption
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
node may be masochistic rom r vastava_
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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
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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
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 119
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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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
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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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
Web: www.crtwireless.com
Ph: (540) 230-6012
Email: [email protected]
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