Fundamentals of Cognitive Radio Technology
Seminari Fondazione Ugo BordoniNew Frontiers in the Management of Radio Spectrum
June 2009
Dr. Joseph Mitola IIIDistinguished Professor, School of Engineering and Science,
Distinguished Professor, School of Systems and Enterprises, andVice President for the Research Enterprise
Stevens Institute of Technology
Domain-Independent Systems Engineering
http://www.stevens.edu/sit/2
Overview• Foundations
– Saturated Commercial Peak Loading– Low Average Spectrum Occupancy
• Dynamic Spectrum Research and Rule Making– WiFi – Fiber Proliferation– Regulatory Perspectives: European Workshops– FCC R&O
• Innovation in Spectrum Management– Advanced Services: 3D, Multisensory– Key Challenge: Rule Complexity and Cost
3
GSM, UMTS Saturated
Spectrum Fully Allocated, Saturated at Off-Peak Hours
4
Low Average Utilization
2 GHz
500 MHz
[© UC Berkeley, 2004, Used with Permission] 5
Policy Lanes in the RoadPolicies
1. Stay between lines
2. Do not hit other cars
3. Don’t run over things
Cars
If Cars and Responder Vehicles Can Share the Road, Why Not the Spectrum?
First Responders
Stay in lanes
Behaviors
Can block lanes
6
A Spectrum Pool Etiquette
© 1997-2007 Dr. Joseph Mitola III
7
8
Z m2
Cell Area
Frequency Reuse Creates Spectrum
System = N Cells
Physics of Spectrum Pooling
Public SafetyCell Area
Cost Includes Backhaul
Pooled Spectrum EtiquetteAdvertise (NB-CDMA)
Backoff Politely to Legacy Users
© 1997-2007 Dr. Joseph Mitola III 9
Ideal Cognitive Radio Architecture
User
Environment
Antenna RF Modem Baseband User Interface
Hardware
INFOSEC
Protocol Stack, ControlModem, Equalizer, etc.
Software RadioSoftware Modules …..
KnownSelf
RXML = Radio eXtensible Markup Language
Cognition CycleCognition
EnvironmentSpace-TimePropagationNetwork
Meta-SoftwareAntenna RF Modem
INFOSECBasebandUser Interface
Equalizer Model
Variable Bindings
...
User(s)IdentityNeedsBehaviors ...
RXML FramesOntologiesDescriptorsEffectors
Adapted from Cognitive Radio Architecture (Wiley 2006) with permission
© 2006 Dr. Joseph Mitola III Used with Permission 10
Dynamic Spectrum Research and Rule Making
FCC Report and OrderCognitive RadioTV Whitespace
Spectrum Management
SDR Forum Workshop: Regulators Address “Social Contracts”FCC: Rules Must Balance Economics with Public Interest
Regulatory Perspectives: Japan NICT/ARIB, UK Ofcom, Germany
12
Power Density vs. Occupancy
© 2005 Shared Spectrum Company (Dr. Mark McHenry) Used with Permission – Overlay © 2007 Dr. Joseph Mitola III
Processing Gain
Antenna Gain
Duty Cycle
13
Dynamic Spectrum
Primary (Licensed) Spectrum
Cellular 1G 2G CDMA 3GPP
Underlay: Ultra Wide Band (UWB)
Noise Temperature
Cordless Telephones: Analog, DECT …WLAN: 802.11 a/b/b WiFi …WPAN: 802.15, BlueTooth, HomeRF
Unlicensed Spectrum (Part 15)
Space-time UseageConsiderations
© 2006 Dr. Joseph Mitola III Used with Permission
Exciting Research and Development
Overlay: OFDM Water Filling
Measurements © 2006 Shared Spectrum Company, Used with Permission
14
Dynamic SpectrumOFDM “Water”
Multiple Input Multiple Output
(MIMO)
Beamforming
How Fast Will the
Water Rise?
© 1997-2007 Dr. Joseph Mitola III 15
Complexity of Space-Time-RF
© 2006 Dr. Joseph Mitola III Used with Permission
© 2000 RF-CAD
Higher Fidelity Sharing by Primary and Secondary Users
16
17
Horizontal and Vertical Artifacts Strongly Influence Path Loss
Signal Subspace Dynamics
© 1997-2007 Dr. Joseph Mitola III © IEEE Academic Use
Complexity of Multipath
Multiple Input Multiple Output (MIMO)
y(t)
x(t-τ2)
1st Bit
x(t)
2nd Bit
x(t-τ1)
3rd Bit
© 1997-2007 Dr. Joseph Mitola III
© 2007 Stephen Fast, Remcom
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Multiple Element Antenna ArraysPatented by ATT as BLASTDeveloped by Europe as MIMOMultipath Enemy Friend3x to 10x Capacity of ShannonBring MIPS
© MIT Lincoln Laboratory
FCC R&O Provisions
• Power Limits– 100 mW– 40 mW Adjacent Channel
• Web Database Access– Database indicates prohibitions– Whitespace devices must access database– Daily access for use– No access (to database) ⇒ No access (to spectrum)
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IEEE P1900.5 Policy Language
[ XG Policy Language R. Krishnan et al, BBN]
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Innovation in Spectrum Management
Policies, Policy Languages, and Behavior Modeling for Autonomous
Conformance to Policy Intent
Cognitive Radio Evolution
• Cognitive Radio Foundation Era (1990-2005)– New radio spectrum with new RF technology– Grow markets via services (GSM) and products (WiFi)– Cognitive radio introduced as far term idea (1998)– Cognitive radio R&D: DySPAN, CROWNcom, XG…
• Cognitive Radio Evolution Era (2005-2020)– Dynamic spectrum approved for low power devices– Behavioral policy languages for spectrum management– Cost of conforming to policies/exceptions is growing– Sentient spaces paradigm establishes expectations[J. Mitola III, “Evolution of Cognitive Radio Architecture” Proceedings of the IEEE, 2009]
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Use Case Evolution
Use Case Parameters Foundation era (1990-2005) Evolution era (2005-2020) Core wireless use cases Towards ubiquitous access Towards integrated services Profit margins High (handsets-infrastructure)
then handset profits declining Low (handsets-infrastructure) to high for differentiated services
Value proposition QoS (Connectivity, data rate) QoI (User is the 8th OSI layer) PSTN integration SS7[1], SDH[2] IP-SIP [3], Mobile IP, or IPv6[4] Reconfigurable HW Not worth the cost vs chipset Transitioning to mainstream? Location awareness Niche applications Ubiquitous Multimedia Infeasible to feasible Strong differentiator Spectrum awareness Within allocated band Across multiple bands Spectrum Auctions Large blocks for long term Small space-time holes short term Public safety Distinct markets Integration with agility Data rate framework Stationary, walking, vehicle Hot spot, traveling, emergency Sentient Spaces Video surveillance markets Elder care and home robotics
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Interactive TV
HDTV
Computing: Moore’s Law
Cognitive Radio Domains
Wireless 1G, 2G GSM-PHS, 3G CDMA, B3G OFDM
Wireless Web
WiFi, WiMAX, OFDM
Land Mobile, Emergency, TETRA …
B3G
MIMO
> 100 Mbps
???
Security, Privacy
Broadcast TV
Cognitive Radio
Dynamic Spectrum
Blue tooth
time
complexity
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Transportation Domain View
Wireless 1G, 2G GSM-PHS, 3G CDMA, B3G OFDM
Wireless Web WiFi
Land Mobile TETRA …
B3G
MIMO
> 100 Mbps
???Cognitive Radio Networks and Users
Blue tooth
Highways
EZ-Pass Tolls
Vehicle Enablers
- As Base Station
Interactive TVHDTV
Security, Privacy
Emergencies
Law Enforcement
Vehicular Enablers
- Integration
- As Base Station
Ports
Container ID
Shipboard AIS
- Robotic Ports
OnStar
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Security Often Comes Last• Radio Security Research @ Stevens
– Compromising emanations, weak codes and ciphers• Radio biometrics (turning TX nuances into trustable IFF)
– Inherently Trustable Comput-ications Technology– Post-quantum Cryptography– Password-reset Guessing from Google & Psychology
• Evaluate military operations security (OPSEC)• Foundations
– Discrete mathematics, Galois fields, problems– Cryptographic algorithms (AES) and systems (Kerberos)– Attacks fall mainly outside of “crypto” per se– Large scale cybersecurity (Secure Systems curriculum)
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A Port as a Secure Resilient Space
Spectrum Management Allowing Device Autonomy
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Cognition Based Services
Axis 207W
© 1997-2007 Dr. Joseph Mitola III
Ambient Intelligence Challenges Spectrum Management
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Multisensory Perception
Characters
Tokens/Words
Phrases
Dialogs
Scenes
Obs
erve
Pha
se H
iera
rchy
of R
einf
orce
d Se
quen
ces
Acoustic Sensors
Phonemes
Words
Phrases
Dialogs
Scenes
Keyboard/email Speech Vision
Scene
Place
Time
Vision Sensors
Texture
Objects, Flows
Expressions
Text ScanPHY
Protocols
Applications
RF-Location
RF Environment29
GSM Saturated but…
Dynamic Spectrum Available
[Riva Networks GSM Basestation]
Low Power, Building Shadowing, Creates GSM Reuse Opportunities
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Building Shadows, Multipath and Reflections
WiFi 1 Mbps VoIP Coverage (Green)
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Virginia Tech
AT&T
Polytechnic
Ground Truth
Polytechnic
908 MHzRosslyn, VA
Building Down
Penn State - < 2 dB Average Error
2 ½ D RSSI Estimation3D/4D CAD
MIMO PerformancePrecision Etiquette
© 1998 Penn State ARL
Contemporary 2 ½ D RSSI Estimation
RSSI – Received Signal Strength Intensity
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RF Spatial Energy Distribution
© 2008 Remcom
© 2008 Remcom
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Wireless LAN (WiFi) Proliferation
© 2006 Scientific American used with permission
DHCP-SIP On Steroids
© 2006 Scientific American used with permission
© 2006 Scientific American, Used with Permission
MIMO-Mobile
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Cognitive Radio Economics Domains• Transportation – Emergency Response
– Next round of innovations• Agriculture
– Robotic on-farm carts, packaging machines– Reduce Sushi-Sashimi Time Lines
• Elder Care– Video-speech-RF scene integration
• Military and Coalition Partners– Higher risk R&D for leap-ahead innovation– Domains overlap all commercial domains
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Radio Architecture Evolution
Observe
OrientEstablish Priority
Plan
Decide
ActOutsideWorld
Send a Message
Receive a Message
Set Display
Read Buttons Save Global States
Allocate Resources
Initiate Process(es)
Generate Alternatives
Evaluate AlternativesParse
Pre-process
Infer on Context Hierarchy
UrgentImmediate
Normal
Register to Current Time
PriorStates
NewStates
Learn
iCR Arcitecture
Haykin Radio-Centric
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Machine LearningR
epre
sent
atio
n Sp
ace
Numeric
Symbolic
Learning StrategySupervised Unsupervised
ArtificialNeuralNetworksPowerful GeneralizationPerformance DegradesWhen IrrelevantFeatures are Present
ConceptualClusteringSet Cover UsingGeneralization &Specialization Decision Trees
Prod
uctio
n R
ules
Feat
ure
Vect
ors
Pred
icat
e C
alcu
lus
FeatureClusteringSet PropertyReinforcementEstimation overMeasurements,DocumentsSVM, Rough Sets
AbductiveInferenceOccam’s RazorOver StructuredFeature Spaces
Wor
d Ve
ctor
s
N-G
ram
s GeneticAlgorithmsBlind Learning, RobustSlow, Massively ParallelConstrained by the Coding of Chromosomes
Case-BasedStorage of ExamplesMemory BasedNearest-NeighborInductive RetrievalAdapt Pre-StoredSolutions to CurrentSituation(Does not requirea-priori model of the solution space)
Knowledge-BasedStructure backgroundknowledge in Rule BaseAcquires New RulesMay Use Certainty Calculus
EntropyNetworkLogic TreeTransformedto Neural Net(N-0.5, 0.5)
HiddenMarkovModels
Concept-BasedAcquires NewPredicates Tieresias
CLARION
© 2006 Dr. Joseph Mitola III Used with Permission 37
Secondary Use Concepts
38
Policy Language Foundations
Semantic Web
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Problem with Policy Languages
• Policy Language = Computer Language– Symbols and rules (define grammar)– Semantic web uses relationships for meaning
• Policy Makers Use of Language– Lawyers, economists, businesses– Language refers to “best practices”– Language of Prior Experience
≠ Computer Language
• Why?
40
Spectrum Management via Cognitive Linguistics
< Bayi-Balan/>1
<Person/>
<Woman/><Frau/>
<Man/><Mensch/>
<Li/>
<Giraffe/>
<Animal/>
<Chair/>
Neonatal DevelopmentThings are earliest fundamental gestalts
Mother-self differentiation, reinforcementPlaces (stomach, home, box) containment
<Teenage Bride/>
Analytic
<Mommy/>
Experiential
Semantic WebCYC, SUO, SUMO, FOAF
1. In Dyirbal culture, the concepts male and female cannot be combined
Lakoff Basic Categories
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Cognitive Linguistics Metaphors• Things [Lakoff-Jackendoff]
– Body experience of physical things: touch, eat, don’t eat, don’t touch• Mind metaphor: ideas, good ideas, bad ideas
• Places [Sensorimotor interaction with a Thing] Video Game– Body is container: eat/ defecate, drink/ urinate, feel good, get sick– Room is a container in which we are contained
• Activity is a place: goodness, success, failure, consequences– Non-visual space continues to exist: [certain] abstractions are real
• Paths [partially ordered (<) set of Places] [Lakoff-Jackendoff]– Physical movement experience
• Activation is motion metaphor; Activity is journey (plan) metaphor• Actions [Thing moving down a Path] [Mitola]
– Anger as burden, dangerous animal, opponent, fire, heat• Causes [Thing.Action that initiates or modulates Action] [Mitola]
– Some Thing initiates {some [other] thing to move down a path}• Reason via metaphor: bodily experience => internal experience => expertise
=> abstraction => logic, language as shared experience
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LJM Basic Types for Radio
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Cognitive Linguistics for Dynamic Spectrum
• Lakoff[1], Jackendoff[8], Ziemke[2], Mitola[6]– Language: pointer to sensorimotor behavior– Reasoning: metaphor (bindings) not logic
• LJM Cognitive Linguistics Orthogonalization– <Thing/> The most common entities in a domain– <Place/> Named vector fields for <Thing/>– <Path/> Associated <Places/> (sequence, hierarchy)– <Action/> Motion of <Thing/> on <Path/>– <Cause/> <Thing/> initiates-constrains <Action/>
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Cognitive Linguistic Modeling of Radio
Things “Everybody knows”
CLA first identifies the few universally common Things of a domain
Places are the vector fields that characterize interaction possibilities for each Thing
Places “Near Field, BLOS”designate subspaces
Paths are sequences of places through which action may occur
Paths “Multipath, MIMO”Basis for actions
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Modeling Radio DynamicsAction is the movement of a Thing along a Path
Actions“TX, RX”Induces
What happened
Transmit: Signal-In-Space = Thing.new(Tower)
Cause is the Thing that initiates an Action
Causes“ETSI”
ConstrainsWho to fine
Air Interface * Channel State
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Genetic Programming [7]
• Specialized form of Genetic Algorithm (GA)• Population of Individuals
– Genome: Set of software components {+,-,if …}– GP Gene: Program tree or script per individual– Random initialization of [working] programs
• Iteration of populations to enhance fitness– Run programs on problems to evaluate fitness– Propagate, procreate, prune, cross-over, [mutate]– 1000 individuals/ 100 populations vs 20/10
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SWR, SDR, DySPAN, and CR Domains
PHY
MAC
Network
…
Application
User
Location
Health…
Context
HW FW SWTX/RX
SWR Band
Ideal Cognitive Radio (iCR)Cognitive WirelessNetworks (CWN)QoI
Speech VisionRFSensory Perception
“CR0” – Dynamic Spectrum
Location Aware
Voice, Data, Video AdvancedGUI & QoI
© 2007 Federal Communications Commission, Used with Permission
SDR (Handsets)
Context Aware…
…
QoS
48
Regulatory Parallels: FCC-NTIACommercial Domains (FCC)
Military Domains (NTIA)49
Conclusions• Cognitive Radio
– Dynamic Spectrum Plus New Opportunities• Systems Engineering Approach
– Smarter Devices– Secure, Resilient Businesses, Homes, Ports– 3D RF-Video Sensor Integration
• Economics of Spectrum Management– Minimize Capital Expense for Infrastructure– Minimize Operating Expense for Services– Sustains social contracts
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References1. George Lakoff, Women, Fire, and Dangerous Things ()19872. Ray Jackendoff, Semantics and Cognition, volume 8 of Current Studies in
Linguistics Series. MIT Press, Cambridge, Massachusetts 1983. 3. John R. Bender. 2001. Connecting language and vision using a conceptual
semantics, Master’s thesis, Massachusetts Institute of Technology.4. Keith Bonawitz, Anthony Kim, and Seth Tardiff, An Architecture for Word
Learning using Bidirectional Multimodal Structural Alignment Report for NSF Award IIS-0218861 W03-0605.pdf (Cambridge, MA: MIT) 2003
5. Peter Gärdenfors, “Representing actions and functional properties in conceptual spaces,” Body, Language, Mind: Embodiment T. Ziemke et al, Editors (Berlin: Mouton de Gruyter) 2007
6. M. Johnson and T. Rohrer “We are live creatures: Embodiment, American Pragmatism” in T. Ziemke, Ibid
7. John Koza, www.genetic-programming.org; Genetic Programming (Volumes 1 [92, MIT Press] through IV [Kluwer, 2003])
8. Jing Liu et al, “Moving Block Sequence and Organizational Evolutionary Algorithm for General Floorplanning with Arbitrarily Shaped Rectilinear Blocks” IEEE Trans Evolutionary Computation (NY: IEEE Press) Oct 08
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Supplementary Material
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Space-time Context
Spatial Context Plane CharacteristicsLevel Plane Members Space Time Contexts1 Global Regions 10,000 km year Itinerary2 Regional Cities 1000 km week Plan3 Metro Districts 100 km day Commuting4 Local Buildings 1-10 km hour Lunch5 Immediate Rooms meters minutes Dead reckoning6 Fine Scale Furniture wavelengths µsec Habit7 Internal HW, SW microns ns Architecture
Resource Description Framework (RDF)/Schema DARPA Agent Markup Language (DAML) Ontology Web Language (OWL)“Semantic Web” – Slow to Catch On
© 1997-2007 Dr. Joseph Mitola III
Knowledge Engineering Bottleneck
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CLM Radio Image Schema
AM-FM-OOK
FDM FSK-PSK TDM
1G
FDMACoding
2GMSK
TDMA
CDMA
3G
Femto
MIMO
Welcome to the Cognitive Radio “[Physical Layer] Signals” VillageA Cognitive Linguistics Center-Periphery Image Schema
55
Machine Learning and Policy
56
Function Conventional Self-Aware Remarks
Iterate Programmers learn through practice
Loop detect M&S Engines
Acquire Architect defines blocks Learn blocks CBR, RL
Encapsulate Define block boundaries GP per platform Over self-descriptions
Apply Compile, ignore internals Semantic model Behavioral properties
Explain Diagnose via IDE, logs, instrumentation
Re-iterate Causal modeling (vs rule unwrapping)
Signal Detection GPSignal genes: s*.s, PSD, max(*), …Detection GP chromosomes (Places anchored to CL Things):
Prepare Signal : get, normalize, s.*s, …Estimate Spectrum : FFT, PSD.walsh, …Extract Parameters : max(Sp), peaks(Sp), …Assert Estimate : Index = Ri; Value = Rj;Prepare result: (Ri -> fc)
Script is a sequence of function calls defining a PathScript = Path: Signal.unknown … Spectrum.known)
Fitness FunctionsConsistency with Training Things-Places and Signal Models
Progress: spectrumGA writes Matlab code; learns new spectra
57
Cognition Includes Self Awareness
Capabilities
Resources
Self
Dialogs
Scenes
Obs
erve
Pha
se H
iera
rchy
of R
einf
orce
d Se
quen
ces
PHY
Protocols
Applications
RF-Location
Dialogs
Scenes
Self-Perception RF Environment User’s Perception
tn
Scene n
Place
Time
Sensors
Primitives
Objects, Flows
User
Self Scan
58
Space-time-RF Etiquette
1 – Don’t jam other users2 – Overcome interference3 – Create affordable,
effective wireless connection
1
Radiated Power
Interference2
3
BeamformingOr MIMO
© 1997-2007 Dr. Joseph Mitola III Permission for Government Use Only 59