Transcript Document

Cognitive Radio Technologies
Applications of Game Theory to CR
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Material
• A little about CRT
• A little game theory
• GT + CR Networks
• GT, CRN and CJ
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Material
• A little about CRT
• A little game theory
• GT + CR Networks
• GT, CRN and CJ
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Cognitive Radio Technologies
Business Details
Founded in 2007 by Dr. James Neel and
Professor Jeff Reed to commercialize
cognitive radio research out of Virginia Tech
• 6 employees / contractors
• 07 Sales = 64k, 08 Sales = 127k
• 09 Sales = 394k, 10 (contracts) = 890k
Business Model
• Partner with established companies to spin in
cognitive radio research
• Navy SBIR 08-099 => L3-Nova
• Air Force SBIR 083-160 => GDC4S
• Contract research and consulting related to cognitive
radio and software radio
• DARPA, DTI, CERDEC, Global Electronics
• Position for entry in emerging wireless markets
• Cognitive Zigbee
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Selected Projects
CR Projects
SDR Projects
• Distributed
spectrum
management
for WNW
• Prototype SDR
for software
controllable
antenna
• White Space
Networking
• Fundamental
limits to SDR
performance
TV incumbent user
Other CR user or nonmicrophone
incumbent
Incumbent
or other
CR user
(regulations
permitting)
(except
microphone
user)
Fractional use
of TV channel
Microphone user
f
6 MHz
• Cognitive
gateway with
ad-hoc
extensions
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
6 MHz
Guard
Band
Unused(6 MHz)
• Rapid estimation
of SDR resources
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
CRT’s Value Proposition
• Carry a concept from
• Designing and
fundamental research
analyzing systems to
to prototype
work with interactions
of complex intelligent
agents in distributed
processes
– Matlab, OPNET, HW• Frequent collaboration
in-the loop sims,
prototypes on varying
with DoD contractors
SDRs
and universities
– Across and within
– GDC4S, L3, VT, USF,
UNLV
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
layers 1-3
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Material
• A little about CRT
• A little game theory
• GT + CR Networks
• GT, CRN and CJ
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
CRs don’t just react,
they interact
Outside
World
• Outside world is determined by the interaction of
numerous cognitive radios
Cognitive Radio Technologies
Web: www.crtwireless.com
147 Mill Ridge
Rd,
Ste 212 makes sense for a link, may not work forPh:
(540) 230-6012
•
What
a net
Lynchburg, VA 24502
Email: [email protected]
WhiteFi Channel Adaptation
• Access nodes choose tuple (center frequency,
bandwidth)
– Uses 5 MHz bandwidth
– 20 MHz in 5 UHF channels
• Managed by access nodes with measurements from
clients
• Unspecified form of hysteresis
• Chosen to maximize (N = num clients, c = channel)
MCham  F ,W   N  MChamAP  F ,W    MChamn  F ,W 
W
MChamn  F ,W  
pn  c 

5MHz c F ,W 

1 
n
pn  c   max 1  Ac , n

Bc  1 

Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Acn
Bcn
n
Airtime Utilization
Number AP in c
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
WhiteFi Channel Adaptation
Unstable (Not published)
• Consistent with paper
assumption that AP much
more active than clients
No interference, very high download

1 
pn  c   max 1  Acn , n

B

1
c


MCham  F ,W   N  MChamAP  F ,W    MChamn  F ,W 
n
• Infinite Loop!
– 4,5,1,3,2,6,4,…
Chan.
Utility
(0,0,0)
(0,0,1)
(2.49, 2.49, 2.49) (2.99,2.5,3)
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
0
1
Utility Characterization
(0,1,0)
(0,1,1)
(1,0,0)
(1,0,1)
(1,1,0)
(1,1,1)
(2.5,3,2.99) (3,2.99,2.5) (3,2.99,2.5) (2.5,3,2.99) (2.99,2.5,3) (2.49,2.49,2.49)
2
CRT Proprietary
310
4
5
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
6
7
Game Theory and CR
• Collection of models / tools for modeling / analyzing
interactive decision problems
• Traditional focus on
– Fixed points: Nash Equilibria
– Performance: Pareto efficiency, fairness
• Stability had to be grafted on
– Convergence to a lesser extent
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Potential Games
• Existence of a function (called
the potential function, V), that
reflects the change in utility
seen by a unilaterally
deviating player.
• Cognitive radio interpretation:
V(a)
– Every time a cognitive radio
unilaterally adapts in a way that
furthers its own goal, some realvalued function increases.
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
time
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Exact Potential Game Forms
• Many exact potential games can be
Network-wide
recognized by the form of the utility
function
Objective
Function
Can’t Influence Own
Outcome
Only impacted by self
Sum of minicoordination games
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
This correlation between selfish and social
benefit yields desirable behavior
• Convergence
– *ALL* sequences of unilateral selfish
adaptations induce monotonically
decreasing network interference levels
– For finite waveform sets, completely
unsynchronized adaptations form
absorbing Markov chains
• Optimality of steady-states
– Assuming exhaustive adaptations,
interference minimizers are the only
steady-states
• Stability
– Sum network interference is a Lyapunov
function in neighborhoods of isolated
interference minimizers
– In practice, many minimizers aren’t
isolated, so some hysteresis is needed
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Figure from Fig 2.6 in I. Akbar, “Statistical Analysis of
Wireless Systems Using Markov Models,” PhD
Dissertation, Virginia Tech, January 2007
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Implications of Monotonicity
• Monotonicity implies
– Existence of steady-states (maximizers of V)
– Convergence to maximizers of V for numerous combinations of
decision timings decision rules – all self-interested adaptations
• Does not mean that that we get good performance
– Only if V is a function we want to maximize
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Other Potential Game Properties
• All finite potential games have FIP
• All finite games with FIP are potential games
– Very important for ensuring convergence of
distributed cognitive radio networks
• -V is a is a Lyapunov function for isolated
maximizers
• Stable NE solvable by maximizers of V
• Linear combination of exact potential games is
an exact potential game
• Maximizer of potential game need not maximize
your objective function
– Cognitive Radios’ Dilemma is a potential game
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
16
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Material
• A little about CRT
• A little game theory
• GT + CR Networks
• GT, CRN and CJ
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Interference Reducing
Networks (Dissertation)
• Concept
– Cognitive radio network is a potential game with a potential
function that is negation of observed network interference
• Definition
     I i  
iN
• Implementation:
()
– A network of cognitive radios where each adaptation
decreases the sum of each radio’s observed interference is an
IRN
time
– Design DFS algorithms such that network is a potential game
Web: www.crtwireless.com
with   -V
Ph:
(540) 230-6012
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Email: [email protected]
Bilateral Symmetric
Interference (Dissertation)
• Two cognitive radios, j,kN, exhibit bilateral
symmetric interference if
g jk p j   j ,  k   g kj pk   k ,  j   j  j , k k
• k – waveform of radio k
• pk - the transmission power of
radio k’s waveform
• gkj - link gain from the
transmission source of radio k’s
signal to the point where radio j
measures its interference,
•   k ,  j  - the fraction of radio
k’s signal that radio j cannot
exclude via processing
(perhaps via filtering,
despreading, or MUD
techniques).
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
What’s good for the goose, is
good for the gander…
Source: http://radio.weblogs.com/0120124/Graphics/geese2.jpg
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
An IRN 802.11 DFS Algorithm
(Milcom06)
• Suppose each access node
measures the received signal
power and frequency of the
RTS/CTS (or BSSID) messages
sent by observable access nodes
in the network
Listen on
Channel LC
RTS/CTS
energy detected?
y
n
– Ignore client interference
• Assumed out-of-channel
interference is negligible and
RTS/CTS transmitted at same
power
Measure power
of access node
in message, p
Start
ui  f    I i  f     g ki pk  fi , f k 
Note address
of access
node, a
Pick channel to
listen on, LC
Update
interference
table
n
Time for decision?
y
kN \ i
1
  fi , f k   
0
fi  f k
fi  f k
g jk p j  f j , f k   gkj pk  f k , f j 
Cognitive CRT
Radio Proprietary
Technologies
147 Mill Ridge
Rd,
Ste 212
20
Lynchburg, VA 24502
Use 802.11h
to signal change
in OC to clients
Apply decision
criteria for new
operating
channel, OC
J. Neel, J. Reed, “Performance of Distributed Dynamic Frequency
Selection Schemes for Interference Reducing Networks,” Milcom
2006, Washington DC, October 23-25, 2006
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Statistics (Milcom /
Dissertation)
•
•
•
•
•
30 cognitive access nodes in European UNII
bands
Choose channel with lowest interference
Random timing
n=3
Random initial channels
Randomly distributed positions over 1 km2
60
Reduction in Net Interference (dB)
•
Reduction in Net Interference
70
50
40
30
20
10
Round-robin
Asynchronous
Legacy Devices
0
0
10
20
30
40
50
60
70
Number of Access Nodes
80
90
100
Reduction in Net Interference
Cognitive CRT
Radio Proprietary
Technologies
147 Mill Ridge
Rd,
Ste 212
21
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Asymmetry Extensions
(SDRF07)
• Symmetry not always there
naturally
–
–
–
–
??
Power control
Prioritization
Beamforming
Ad-hoc nets
• Symmetry can be induced by
manipulating observation
processes
– Network optimization correlates
with desired metric, but may not
be desired metric
• Some practical considerations
ignored in pubs.
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
From Phase I Navy SBIR
(“Published” at JSTeF 09)
What if the
environment
is “unstable”?
• Stability impact
• Sources considered
– Dynamic multipath environments
(mobile fading)
– Hostile users
• Performance Impact
Hopping Jamming
Tone
Jamming
Tone Jamming
(Mobile)
(Mobile)
Hopping Jamming
(Mobile)
(Mobile)
Clusters’
Frequencies
0
5
10
15
20
Observed Interference
Levels
0
5
10
15
20
e
lop)
s
ter lity
ea obi
r
G (m
Aggregate Network
Interference
0
5
10
seconds
15
~30 dB
20
• Constraints:
Smaller to zero
gain
Shifted Left
(jammers)
–Irregularly timed observations without collaboration or centralization
Web: www.crtwireless.com
–Preserve performance and responsiveness, minimal complexity
Ph:
(540) 230-6012
–No “special” new measurements
Email: [email protected]
Cognitive CRT
Radio Proprietary
Technologies
147 Mill Ridge
Rd,
Ste 212
23
Lynchburg, VA 24502
Load-Sensitive Routing
(Not published yet)
• Traditional stability issues
when load-sensitive
– Interactions intractable for
ARPANET
• Generalized congestion
game
– Stable and load-sensitive
• Ignores information
distribution
– Each edge is EPG
• Action is contribution of traffic
– Cost = 0 if not using edge
– Path cost is sum of edge
costs
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
CRT Proprietary
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Multi-Layer, Multiple CR Process
Integration (Not published yet)
• Enables stable,
desirable operation of
CRN with multiple
different distributed
processes
– Spectrum, routing, DSA
• Orthogonal
– No interaction
• Edgewise
ce , p  s, r  

f E \ Em
tet f I ef  se , s f

– Effectively MSI game +
Generalized Congestion
• Network wide
Cognitive Radio(products)
Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
CRT Proprietary
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Improving Coexistence
(SDRF TVWS Workshop 09)
1 1   
1 1   

A
  1  





1


• Modfifies BSI to induce “affinity” for
classes of radios
• Leverages database for locations &
classes of radios
• Assumed two step-coexistence process
6
– Distributed sort of fractious networks into
different channels (frequency deconfliction)
– Coordinated coexistence of compatible
networks within channels (transmission time
deconfliction ala .22 or .16h)
1
0
CRT Proprietary
171819
Channel
27
33
38
Final
6
5
# Users
Weighted fairness needs mechanism for
broadcasting weights if weights are
situationally dependent
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
2
7
Limits trunking gains
– Can account for tethered radios without
revealing location / IDs
•
3
2
• Limit frequency deconfliction to when it’s
absolutely necessary
•
Initial
4
# Users
• Can sort themselves out without direct
coordination
5
4
3
2
1
0
2
171819
Channel
Web: www.crtwireless.com
Ph: 27 (540)
230-6012
33
38
Email: [email protected]
Material
• A little about CRT
• A little game theory
• GT + CR Networks
• GT, CRN and CJ
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Malicious != Mischievous
(From dissertation)
• Popular “solution” to
mischievous nodes
(selfish nodes that
damage network) is to
“punish” nodes
– Also implies a way to
“brainwash” learning
nodes
From Fig 6 in [MacKenzie_01]
• Imperfect information can
obfuscate punishment
from mischievous
behavior and produce
catastrophic cascades
• Even with perfect
information, malicious
node may be masochistic
From [Srivastava_06]
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Malicious CRs can blend in
(Not published yet)
Average interference levels for nodes 6-35
5 malicious, 30 normal
– Given available adaptations and
knowledge about network state
– Maximize system (own)
35 dB
performance
• Normal CR
• Malicious CR
– Given available adaptations and
knowledge about network state
– Minimize system performance
35 normal
• Adapt at inopportune times
• Simply minimize
performance
• Ensure marginally stable
network goes unstable
• Plus learning exploits
– And spoofing
CRT Proprietary
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
• And information corruption
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Detecting malicious behavior from
Nash equilibria (Not published yet, but
not that useful )
– Assuming CRs adhere to
specified goals
Predicted
operating point
Allowable region
CR2
• With non-deterministic
decision processes, difficult to
say whether instantaneous
adaptations are “ok”
• Assume we know radios are
trying to maximize specific
goals
• We can identify the expected
operating points
Detected operating point
• But:
CR1
– Predictions depend on
environment
– Doesn’t help identify the CJ
– Convergence to / existence of
NE not generally guaranteed
CRT Proprietary
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Malicious User Detection with
Potential Games (Not published yet)
• Implement as monitoring
system that evaluates
potential (emergent) function
– Frequently sum of
performance levels
– Complexity is in the
transmission / connectivity
– No single node / cluster
knows / can evaluate
emergent function
V
• But a malicious CR will lie
– E.g., Claim massive gains to
offset others’ losses
• With BSI, a malicious node
can’t tell a credible lie!
– Other relationships exist
– Need to be WPG / EPG for
linear relationships
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
CRT Proprietary
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Illustration of using emergent
property to detect malicious CR
Adaptations
120
Channel
120
Channel
Adaptations
140
140
100
100
Policy restricted 80
channels
80
60
60
40
40
0
50
100
150
200
250
0
300
50
-40
-50
I (f) (dBm)
200
250
300
250
300
-60
i
-70
i
I (f) (dBm)
Radio Utilities
-70
150
Radio Utilities
-50
-60
100
-80
-80
-90
-90
0
50
100
150
200
250
300
(f) (dBm)
(f) (dBm)
Potential Function
No Malicious User
-75
Cognitive Radio
0 Technologies
50
100
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
200
250
200
-60
-80
150
iteration
150
-50
-70
-70
100
Malicious User Detected
-40
-55
-65
50
-30
-50
-60
0
300
CRT Proprietary
Potential Function
0
50
100
150
iteration
200
250
300
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
CR/CJ Interaction
(in seedling proposal to Bruce)
• Cognitive radios will be faced with cognitive attackers
– Any fixed mitigation strategy to eventually be learned and defeated
• Partial Solution:
– Model as multi-armed bandit problem (classic machine learning model)
– Use regret learning to achieve near-optimal performance (given presence
of intelligent adversary)
• Issues:
– Bandit (cognitive attacker) strategy nor is solution space constant
– Starting from untrained state may be too long to track assailant
• Proposed Solution to Issues:
– Seed the routines by learning and classifying what attacks are underway
• Effectively adds case based reasoning and attack recognition / learning
CJ is influencing outside world to
intentionally confuse and harm CR
• State at end of seedling:
– Proof of concept simulation and analysis
• Anticipated Benefits:
– Reduce the period of time from when new attacks emerge to when
defenses are implemented
• Intermediate tasks:
– Learn to detect when attacked
• Important to differentiate poor performance from attack
– Learn to classify attacks
– Generalize multi-armed bandit solutions to changing solution space
– Define how to integrate together CBR and bandit solutions into CR
– Characterize “reaction” times (for adversarial OODA loop)
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
CRT Proprietary
Akin to trying to build a HMM,
www.crtwireless.com
while an opponentWeb:
is changing
the
Ph:
(540) 230-6012
states
Email: [email protected]
CRT’s Value Proposition
• Carry a concept from
• Designing and
fundamental research
analyzing systems to
to prototype
work with interactions
of complex intelligent
agents in distributed
processes
– Matlab, OPNET, HW• Frequent collaboration
in-the loop sims,
prototypes on varying
with DoD contractors
SDRs
and universities
– Across and within
– GDC4S, L3, VT, USF,
UNLV
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
layers 1-3
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Extras
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]
Solved issues with game
theory (JSTeF 09)
• For example, for a collection of 802.11 clusters
independently choosing operating frequencies
1. All self-interested
adaptations
• Scalable resource utilization
• No synchronization required
Clusters’
Frequencies
0
2. Based only on
observations of own
performance
• No information exchange overhead
• More responsive network
5
25-30 dB
0
25-30 dB
3. Decrease aggregate
network interference
• Self-stable
• Converges to local-optima
CRT Proprietary
Cognitive Radio Technologies
147 Mill Ridge
36 Rd, Ste 212
Lynchburg, VA 24502
5
0
5
10
15
20
Observed
Interference
Levels
10
15
20
Aggregate
Network
Interference
10
15 www.crtwireless.com
20
Web:
seconds Ph:
(540) 230-6012
Email: [email protected]
– Large capacity gains and
interference reduction
– Without the overhead,
complexity, or the single-point
of failure
– With much better scaling
• O(node density)
– Using generally available
measurements, e.g., RSS,
node ID, time stamps (later)
Cognitive Radio Technologies
CRT Proprietary
147 Mill Ridge Rd, Ste 212
37VA 24502
Lynchburg,
Reduce interference
by 25-30 dB
Network Density
Collision Probability
• CRT’s distributed algorithms
performance equivalent to
“omniscient” centralized
local search algorithm
Steady-state
interference
Gain the performance without
the overhead or complexity
(SDRF07)
Support 16 x more links
Web: www.crtwireless.com
Network Density
Ph:
(540) 230-6012
Email: [email protected]
Cognitive Radio Technologies
147 Mill Ridge Rd, Ste 212
Lynchburg, VA 24502
Web: www.crtwireless.com
Ph:
(540) 230-6012
Email: [email protected]