Cognitive Radio Networks:Cognitive Radio Networks:Imagination or Reality?Imagination or Reality?

Joseph B. Evans

Deane E. Ackers Distinguished Professorof

Electrical Engineering & Computer Science

Definitions and More QuestionsDefinitions and More Questions

• Cognitive• Is it sense – act – learn?• Or learn – sense – act?

• Radio• Radios with the right capabilities exist• But with focus on what layer(s) of the system?• Is the focus on local subsystem and/or single parameter?

• Networks• Information shared across network?• Coordinated actions?

Radios

KU Agile Radio (KUAR)KU Agile Radio (KUAR)

• Compact & portable agile radio

• Consists of RF, digital, and power supply boards

• Flexible hardware• Current KUAR supports 5 GHz band operations

• Future implementation to support 2.4 GHz band• 30 MHz independent Tx/Rx complex baseband

• Waveform: A/D 14-bit @ 80 Msps and D/A 16-bit @ 160 Msps• PowerPC 405 (266 MHz), 32 MB SDRAM / 32 MB Flash• Ethernet• Xilinx Vertex II Pro; 2 PPC cores; 21K logic cells; 300 MHz

• Flexible software • Linux OS (Kernel 2.4)• C++ SCA implementation from Virginia Tech (OSSIE) used for

software framework• KUAR control processor fully participates in wired network with

standard network services

• Capability for dynamic service and spectrum access, and rapid service creation

Cognition and RadioCognition and Radio

Source: Preston Marshall, DARPA

Technology TrendsTechnology Trends

Processing

Memory Storage

Networking

Agile Radios

Cognitive Radio Networks?

Networks

Smarter Nodes to Smarter NetworksSmarter Nodes to Smarter Networks

Across Networks

Within Devices &Protocol Stacks

Within Networks Within Devices &Protocol Stacks

Cognitive Radio ArchitecturesCognitive Radio Architectures• Cognitive radio networking capabilities

• Radio adaptation and collaboration• Spectrum coordination for flexible wireless access • Autoconfiguration• Networking service discovery, naming, addressing and routing• Cross layer network management overlay to provide aggregated

representations of the cognitive subnetwork state to the future Internet

Cognitive Wireless NetworksCognitive Wireless Networks

• Cognitive Wireless Network with Multiple Network-Layer Overlays

Core Network

Supernode(mobile or fixed)

Mobile Nodes

Overlay 1

Overlay 2

The Bottom LineThe Bottom Line

• Adaptation & learning are already in the network

• But…

• Cognition in the network is immature

• Much work needs to be done on proving the concept and then exploring deployment

Cognition

Cognition – For Example, SpectrumCognition – For Example, Spectrum

Source: Preston Marshall, DARPA (Modified)

AutonomousDynamicSpectrumUtilization

SenseReal-time, Wideband

Monitoring

CharacterizeRapid Waveform

Determination

ReactFormulate Best

Course of Action

AdaptTransition Network to New Spectrum Plan

How Cognition Might HelpHow Cognition Might Help

• Each technology can “throw” tough situations to other more suitable technologies

Source: Preston Marshall, DARPA (Modified)

TopologyPlanning

SpectrumPlanning

MIMO

Dynamic Spectrum

Wireless DeviceConstraints

Strong Neighbor Signal

Beamforming Nulling

Relocate Around Constraint

Move to New Band Need More RangeUnavoidable Strong Signal

Re-Plan Topology

Re-Plan AcrossNetwork

Spectrum Too Tight

No Good MIMO Paths

Physical Link

Radio Device

Network-Wide

Radio Device

Distributed Sensing, Control, & LearningDistributed Sensing, Control, & Learning

• Sharing observations from sensing

• Sharing information for reasoning and learning

• Protocols and languages?

Network

Sense

SenseDistributed

Sensing

ActActDistributed

Actions

Models of Expected - Topology - Performance - Use

Collaborative Control

Model ConstructionAnd Updating

Predictive models used to notice

deviation from the expected,

initiate actions

Isolation Alarming Diagnostics

Opportunity in ChaosOpportunity in Chaos

• It may be best to investigate from different parts of the protocol architecture

• Configuration management of radios in a node because of recent trends towards multi-radio systems

• Network management because it is less firmly embedded in the architecture

Final ThoughtsFinal Thoughts

• Radio platforms• They exist, with varying degrees of sophistication

• Adaptation in response to sensing• Most radio systems already do this to some extent

• Learning• It is clearly incorporated on some time scale • But how does it evolve over time?• How it is shared – or networked?

Cognitive Radio Networks:Cognitive Radio Networks:Imagination or Reality?Imagination or Reality?