1

Grand Challenges in Achieving Dynamic Spectrum Access

Preston Marshallpreston.marshall @darpa.mil

Defense Advanced Research Projects AgencyAdvanced Technology Office

Connectionles

s

Connectionles

s

Networks

Networks

Radio-Isotope Micro-power

SourcesOne of

DARPA’s top 5 programs!

•Defense News, June 3, 2002

One of DARPA’s top 5

programs!

•Defense News, June 3, 2002

Wolfpack

Opinions expressed are those of the authors, and do not represent the position of DARPA, the Department of Defense, or the United States Government

PhotonicPhotonic

AvionicsAvionics

Retro-DirectiveNoise

CorrelatingRadar

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Adapt,Morph,

Proliferate

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2006 Technology and Policy for Advanced Spectrum

Exploiting

Exploiting

2

The Next Challenges

• Dynamic Spectrum is on It’s Way to Accomplishment

• Key to Adoption is the Widest Possible Range of Benefit

• Better Spectrum Management is Important, ….– But May not be the Sole or Most Effective Argument

for its Adoption

• Need to Research Network Capability Enabled by Dynamic Spectrum– How Can We Exploit Truly Dynamic Networks?– Understand Physical Layer Bandwidth Sharing– Create (and Tear Down) Topologies Every Second

Why Just Put Dynamic Spectrum in Static Network Concepts?

3

Some Research Topics Enabled by Dynamic Spectrum (Partial)

• Adaptive Topology– Just in Time Connectivity– Don’t Do Topology Discovery – Do Topology Creation

• Non-Linear Effects Mitigation– Look at Total Energy – Not Just One Frequency

• Adaptive Spectral Bandwidth, Modes, ….• Optimization of Networks with No Fixed Bandwidth,

But some Interactions due to Shared Spectrum Resource– …. Oh, and update them every second!

• How Can Dynamic Spectrum and MAC Layer Operation Be Fused– Cooperative and non-Cooperative Channel Sharing

These Topics Have No EquivalentWired IP Metaphor

4

Discussion Points

• Overarching Thrusts of the DARPA Adaptive Networking Programs

• Current Technical Progress in Adaptive Spectrum

• Future Issues with Growth of non-Linear Effects (Front End Linearity)

• Leveraging Adaptive Spectrum to:–Lower Device Cost–Address Dense RF Environments–Create Adaptive Network and Services

5

XYZ.COM

Infrastructureless Networking:How Do I Network Without?

CentralCentralServersServers

CacheServers

KnownTopology

Frequency &Frequency &Network Network PlanningPlanning

Enter SearchIndex Index

ServicesServicesFiber &Wires

Cell Towers UnlimitedUnlimited

EnergyEnergy

6

Technology Implications

Current (Possible) Future

• Extensive Pre-Planning • Self Monitoring and Adaptation

• Fixed Network Structure • Self Forming

• Asymmetric, Hub-Spoke (ex. Cellular, VOIP)

• Peer to Peer

• Separate Network and User Equipment• Security at the Perimeter• Services and Info at Core

• User Equipment is the Network• Distributed Security • Info at Edge

7

How Can We Operate in a Wide Range of Environments, Missions, Densities, …

• Device Adaptation is Key to Needed Technology– Self Organize to Operate Without Infrastructure

• But Leverage Whatever Infrastructure is Available– Locate Unused Radio Spectrum

• While Ensuring no Interference to Other Users• Continuously Measure Environment• Avoid Need for Detailed Pre-planning, Deconfliction, …

– Morph Physical and Media Access Layers• Leverage Multi-path with MIMO• Select Waveforms, bandwidths, Access Control Mechanisms

– Apply Multiple Network Topologies• Optimize Packets, Streams, Multicasts, …

– Adapt Topology to Mission and Opportunities• Opportunistic (instead of Fixed) Topology• Continuously Adjust Topology to Meet Instantaneous Network Needs

• And Do All this at New Levels of Affordability– Essential to Achieving Required Density– Adaptation Can Mitigate Engineering Performance

Compromises and Use Less Costly Devices

8

Some Wireless Networking Research Programs at DARPA

• neXt Generation Communications (XG)– Develop Technology to Sense and Situationally Adapt Spectrum

Usage for a 10 Times Increase in Spectrum Access• Disruption Tolerant Networking

– Extending the Network Framework to Include Storage and Delivery for Episodic Networks• (Leverage Whatever Connectivity is Available)

• MnM Mobile MIMO– Extending Multiple Input/Multiple Output Technology to Mobile

Platforms for a 9 times increase in Throughput• Wireless Network After Next

– Develop the Technology for Dense, Low Node Cost (Under $500) Networks with High QOS

• Connectionless Networking– Dynamically Adapting Network Time Synchronization, Routing,

Energy Strategy to Achieve High Performance at 100th the Energy

9

Some Wireless Networking Research Programs at DARPA (Continued)

• Polarization Rotation Modulation– Encode Information in Polarization to Achieve a 9x More Space

to Space and Space to Ground Bandwidth

• Radio-Isotope Micro Power Sources– Power “Manufactured In” for Life of Device

• Ultra-wideband Networking (NETX)– Close in LPD Communications in Harsh Environments– Very High Accuracy Positioning

• Spatial Optical (Air/Air and Air/Ground)– “Wireless Does Not Always Mean RF!” – Adapting for the Reliability of RF, and Speed of Fiber– Air to Air and Air to Ground Providing for Wireless

Communications at Fiber Speeds (ORCLE)– Passive Optical Tags that provide 100’s of Kilobits/Sec

10

All Spectrum May Be Assigned, But…

…Most Spectrum Is Unused!

XG is Developing the Technology and System Concepts for DoD to Dynamically Access All Available

Spectrum

React

Formulate Best Course of Action

ReactReact

Formulate Best Formulate Best Course of ActionCourse of Action

Adapt

Transition network to new emission plan

AdaptAdapt

Transition Transition network to new network to new emission plan emission plan

Characterize

Rapid waveform determination

CharacterizeCharacterize

Rapid waveform Rapid waveform determinationdetermination

Sense

Real time, Low-power, wideband

monitoring

SenseSense

Real time, LowReal time, Low--power, wideband power, wideband

monitoringmonitoring

AutonomousAutonomousDynamic Dynamic SpectrumSpectrumUtilizationUtilization

DARPA XG Program

Goal: Demonstrate Factor of 10 Increase in Spectrum Access

Maximum Amplitudes

Frequency (MHz)

Am

pli

du

e (

dB

m)

Heavy UseHeavy Use

Sparse UseSparse Use

Heavy UseHeavy Use

Medium UseMedium Use

11

DARPA XG Program Investments

XG PrototypeXG Prototype& Demonstration& Demonstration

Spectrum AwarenessSpectrum Awareness

InterferenceInterferenceEffectsEffectsAssessmentAssessment

BehaviorBehavior

AdaptiveAdaptiveNetworkNetworkOperationOperation

Spectrum Measurements

Sensor Technology Signal Processing Algorithms

Distributed SensingAlgorithms

IEEE 1900IEEE 1900PolicyDescription

Spectrum AdaptiveNetworking

OptimizingStrategies

PolicyReasoning

Capabilityand Affordability

Dynamics

SubnoiseDetection

IncreasedAwarenes

s

PerformanceExperiments

Methodology

Framework &Semantics

EngineeringBasis

Non-InterferingOperation

Tactics

PolicyLanguage

EnforcementImplementation

Assessments

12

Transceiver

SystemStrategy

Reasoner

XG Operation

Select

Opportunities

PolicyReasoner

DevelopOptions Process

Request

Determine

Opportunities

Yes/No or Additional

Constraints

AccreditedPolicy

RF Info Acquisition

Sensing Loop

Policy Engine

RadioPlatform

Me

ss

age

Flo

w

RF ResourceRequest

RF Transmit Plan

13

What We Expect

• Simulation of Early Designs Using Recorded Spectrum Measurements Shows Significant Potential

Data from Lockheed Martin, Raytheon, and Shared Spectrum Company models

90% Spectrum Access at 90% Connectivity

Typical Spectrum Occupancy ~6%

10x increased spectrum access10x increased spectrum access

Multiple XG BandwidthsMultiple XG Bandwidths

14XG 098 v3

Non-Cooperative XG Network

Cooperative XG NetworkHomogenous

XG NetworkUGS

XG Nodes EmulateMultiple Radio Types

XG Policy Administratorand Analyzer

DemonstrationController

Wide Variety of Un-cooperative Nodes

Satelliteback-haulinstrumentation links

Wide Variety ofNon-cooperative Nodes

XG Prototype Developmentand Demonstration Schedule

• Conduct Series of Field Demos– Incrementally Add Performance

• Midterm Demonstration (Demo 3)– 6 Nodes with Core Capabilities– Provide Confidence to Stakeholders

• Final Demonstration – 25 XG Nodes with Advanced Capabilities– Show Capability for Transition

XG 008 v6

Task Name

DemonstrationsCriteria Dev’t1. Two Node2. Five Node3. Technology4. Initial System5. Upgraded System6. Final Configuration7. Final Urban8. Final Test Range

3

78

12

56

4

#1 demonstrates:2 nodesDemo Spectrum PolicyPerformance DetectorRendezvousFrequency Selection

# 6, 7, & 8 Demonstrates All Technologies

#2 adds:6 nodesGroup Behaviors

#3 adds:6 mobile nodesNetwork FunctionsLow Power Detector

#4 adds:Policy EnforcerUltimate Modem

#5 adds:25 mobile nodesEnhanced Detector

Phase

3aPhase 3b Phase 3c

XG 008 v6

Task Name

DemonstrationsCriteria Dev’t1. Two Node2. Six Node3. Technology4. Initial System5. Upgraded System6. Final Configuration7. Final Urban8. Final Test Range

3

78

12

56

4

#1 demonstrates:2 nodesDemo Spectrum PolicyPerformance DetectorRendezvousFrequency Selection

# 6, 7, & 8 Demonstrate All Technologies

#2 adds:6 nodesGroup Behaviors

#3 adds:6 mobile nodesNetwork FunctionsLow Power Detector

#4 adds:Policy EnforcerUltimate Modem

#5 adds:25 mobile nodesEnhanced Detector

Phase

3aPhase 3b Phase 3c

15

Demonstration Objectivesto Show:

• No Harm– Detects Potential Victims Before Causing Harmful

Interference– Disseminates Sensor Data For Spectrum Awareness– Incorporates Automated Spectrum Rule Enforcement

Algorithms

• XG Works– Demonstrates Automated Rendezvous and Frequency

Selection– Enables Node Transitions Between Networks– Conducts Operations With Multiple Cooperative and Non-

Cooperative networks

• Adds Value– Increases Spectrum Access and Communications Capacity– Implements No Setup Networking– Implements Automated Spectrum Rule Updating Algorithms

16

XG Radios (mobile)

NC DoD Radio (fixed)

Equipment Installed in Vans

NC DoD Radio and Test Equipment XG Radio and Test Equipment

Legacy Radio Link

XG Link

17

XG Behaves!!

With XG – Sense and Jump Without XG – Signals Collide

With XG -- Moved Before Interfering

XG halts transmissions when RX link is broken (dropout caused by propagation losses)

Near instantaneous channel reestablishment

Successful channel reestablishment during extended link dropout

18

Speeded Up Transit of XG Past a Set of Non-Cooperative Radios

• Colors are Different Frequencies

• Dots are XG Radios• Triangles are non-

Cooperative Networks• XG’s Always try to be

on Lowest Frequency Possible (Blue)

19

Simple Scenario, With and Without XGMilitary PSC-5 FM Radio Victim

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

11

:40

:04

11

:40

:14

11

:40

:24

11

:40

:34

11

:40

:44

11

:40

:54

11

:41

:04

11

:41

:14

11

:41

:24

11

:41

:34

11

:41

:44

11

:41

:54

11

:42

:04

11

:42

:14

11

:42

:24

Time

p

0

200

400

600

800

Victim Radio Bit Error Rate Without XG

Scenario Time

Bit

Err

or R

ate

XG Caused Noise

No

de

Se

pa

rati

on

(m

trs

)

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

12:5

5:05

12:5

5:15

12:5

5:25

12:5

5:35

12:5

5:45

12:5

5:55

12:5

6:05

12:5

6:15

12:5

6:25

12:5

6:35

12:5

6:45

12:5

6:55

12:5

7:05

Time

0

200

400

600

800

Bit Error Rate With XG

Bit

Err

or R

ate

Typical impulsive Environmental Noise

Scenario Time

No

de

Se

pa

rati

on

(m

trs

)XG Node

Interferes within 600 meters

Only Background

Impulsive Noise

20

XG Strategy

• XG is not the universal solution to all problems– Some cases are likely to be too hard to deal with– One hard case does not does not invalidate XG usefulness

• Testing to be focused on identifying and validating– low hanging fruit– candidate spectra that are unsuitable for sharing

• Anticipate incremental adoption on a “Not to Interfere” basis– Military on military (10x greater packing of radios)– Military on shared (Technical framework for sharing)– Opportunistic (Widespread NIB operation)

Not Essential to Establish New Regulatory Framework, either

Nationally or Internationally

Not Essential to Establish New Regulatory Framework, either

Nationally or Internationally

21

Policy Compliant Behavior

• Rejected Notion that General Solution to Adaptive Radio Could be “Just Code”– Almost 200 Sovereignties– Thousands of Bands– Emerging Technologies

• Investing in Computer Science Structure for Policy Reasoning– Reasoning Technologies to Control

Real-Time Process– Declarative Language Expression– Provable Policy Expression and

Implementation • Partitioned Policies into Two

Categories– Policy Enforcement (Permitted

Operation)– Optimizing (Network and Above)

Secretary of State Telecommunications & Public Information

Secretary of State Secretary of State Telecommunications Telecommunications & Public Information& Public Information

Ministry of Communications

Ministry of Ministry of CommunicationsCommunications

Regulatory Authority of

Communications & Posts

Regulatory Regulatory Authority of Authority of

Communications Communications & Posts& Posts

Regulatory Authority of Telecommunications

and Posts

Regulatory Authority of Regulatory Authority of Telecommunications Telecommunications

and Postsand PostsMinistry of Public Works, Transport,

& Water Mgt

Ministry of Public Ministry of Public Works, Transport, Works, Transport,

& Water Mgt& Water Mgt

Department of Trade & Industry

Department Department of Trade & of Trade & IndustryIndustry

Ministry of Science,

Technology, & Innovation

Ministry of Ministry of Science, Science,

Technology, & Technology, & InnovationInnovation

Ministry of Industry,

Employment, & Communications

Ministry of Ministry of Industry, Industry,

Employment, & Employment, & CommunicationsCommunications

Ministry of Transport &

Communications

Ministry of Ministry of Transport & Transport &

CommunicationsCommunications

Ministry of Civil Affairs &

Communications

Ministry of Civil Ministry of Civil Affairs & Affairs &

CommunicationsCommunicationsMinistry of

Economics, Finance, &

Industry

Ministry of Ministry of Economics, Economics, Finance, & Finance, &

IndustryIndustry

Ministry of Transport &

Communications

Ministry of Ministry of Transport & Transport &

CommunicationsCommunications

Ministry of Infrastructure

Ministry of Ministry of InfrastructureInfrastructure

Ministry of Transport, Posts, &

Telecommunications

Ministry of Transport, Ministry of Transport, Posts, & Posts, &

TelecommunicationsTelecommunications

Department of Public

Enterprise

Department Department of Public of Public

EnterpriseEnterprise

Regulatory

Inte

rope

rabi

lity

Device

Network

RegionalNational

• City-Specific Spectrum Policy

• Waveform Mode• Device Duty Cycle

Limits • Network

Admission Hardware Limits

Security

Admission

Routing

Addressing

Transport

Constantly Shifting

Intersection

22

Future Cognitive Components Will Not Come From Just One Source

Spectrum Policy

Country #1Spectrum

PolicyCountry #2

Device Mfr.Device Mfr.ConstraintsConstraints

Network Network ServiceService

#1#1

Network Network ServiceService

#2#2

IndustryStandard A

IndustryStandard BIndustry

Standard C

Enterprise 2 Enterprise 2 PoliciesPolicies

Enterprise 1 Enterprise 1 PoliciesPoliciesSecuritySecurity

ModeMode SecuritySecurityModeMode

InteroperableInteroperableMode # 2Mode # 2

InteroperableInteroperableMode # 4Mode # 4

InteroperableInteroperableMode # 1Mode # 1

InteroperableInteroperableMode # 3Mode # 3

PersistencePersistencePolicyPolicy

TopologyTopologyOptimizingOptimizing

NetworkNetworkOptimizingOptimizing

MultipleDynamically InteractingCognitiveProcesses

Spectrum LeasingPolicy

23

• Anticipate Incremental Adoption on a Not to Interfere Basis (NIB)– Military on Military (10x Greater Packing of Radios)– Coordinated Sharing (Military

with Coordinated Users)– Opportunistic (Widespread

NIB Operation)

• Incremental Rollout Enables Near-Term Deployment as Appliqué Into Existing Systems– Add Protocols and Adaptation

Software to Digital Networking Radios

– Add Spectrum Sensing Algorithms

XG Program – Transition

Not Necessary to Establish New RegulatoryNot Necessary to Establish New RegulatoryFramework, Either Nationally or InternationallyFramework, Either Nationally or Internationally

24

DARPA Tuner Study Conclusion

•Looking at High Density RF Environments– Even With Ultra-High Quality Front Ends,

Inter-Modulation Will Cause 20 dB (100 Times) Increase in Noise for Wideband Front Ends in Contemplated Density

•Narrow Analog Filters Essential to Survival in Typical Military Dense RF Environments– Can Not Throw Linearity at the Problem– Energy Costs of High Linearity

Unacceptable in Battery Devices•Responsive Strategy

– Accelerate High Performance Tuneable Filter Technology

• 100’s of Individual Filter Settings/Octave• DARPA ASP Program

– Do Not try to Survive on Any Given Frequency

– Use Adaptive Spectrum to

Resolve Remaining

In-Filter Conflicts

INPUT SIGNAL

Post-RF Preprocessing

Non-LinearDistortions

Results Shown for 10w, 10dB Gain, IIP3 = 50dBm (Ultra High Quality) LNA w/ Prime Pwr > 12 Watts

Noise Floor Increases 20

dB!

Even Dynamic Spectrum Can Not Help the Radio with 20 db of Intermod!!

Spectrum Appears to Offer Lots of Opportunities

25

Adaptation Is Key• Without Tunable Ultra-High Q

Front End Filters (Unavailable), Reliable Wideband Radio Operation in Dense Spectrum Can Not be Assured– Legacy Narrow and Fixed Band

Radios Could Rely on Fixed Filters

– Can De-conflict Intended Frequencies, but not Non-Linear Products

– Co-Site Like Situations More Common

– Large Energy Costs for Linearization Unacceptable for Many Applications

• Spectrum Adaptation (as in XG) Essential to Move Around Strong Signals Automatically

0

1

2

3

4

5

6

7

8

-20 -10 0 10 20 30Input IP3

Min

imu

m P

os

sib

le T

un

er

Po

we

rBut,… Even 20

dBm of IIP3 requires at least 5

watts of Prime Power (Ideally)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-80 -60 -40 -20 0 20 40 60Input IP3

% le

ss 5

dB

Int

erm

od N

oise

Fixed Filter

No Filter

Tunable Filter

Feasible

Region

IIP3 > 20dBm Required to

Avoid 50% of Spectrum

Having 5 dB Intermod Noise

26

DARPA Director’s Vision of Communications Technology Evolution

Dynamic Spectrum Future Networks

Mobile Self-Forming

MEMS/NEMS

Packet Radios

Topology Optimizer

Cognitive Technology

Mobile Networked MIMO Program – MNM

Future Combat System – Comms Program - FCS-C

Global Mobile Program - GLOMO

Small Unit Operations-Situational Awareness System Program– SUO

SAS

Wireless Network after Next Program - WNAN

Control-Based Mobile Ad-Hoc Networking Program - CBMANET

Next Generation Comms Program - XG

Information ProtectionDynamic Quarantine of Computer Based Worm Attacks Program – DQW

Defense Against Cyber Attack in MANETs Program – DCMANET

Key to Infrastructureless Comm Key to Infrastructureless Comm

27

What We Need to Do Next

• Develop the Technology to: – Adapt Network in order to Operate Radios with 20 db Lower

SFDR and Linearity at the Same Performance• Existing Programs Provide toolkit for the Physical Layer, but Have

no Network to Exploit the Opportunities – Scale Understanding to Ultra-Large Mobile Networks– Extend Concept of Packet Networks to Directly Implement

Tactical Broadcast /Streaming Service – Operate Multiple Network Technologies Simultaneously to

Meet Each Mission QOS Need

• Achieve:– 100 Time Reduction in Network Radio Cost ($500 per 4

Channel Radio)– 10 Time Reduction in Network Area Coverage Cost– 1,000 Times Increase in Demonstrated and Objective Network

Scale (100’s to 100,000’s)– Higher Goodput/Throughput Ratio to support

Broadcast/Netted Voice/Video

28

Adaptive Radio Uses All Network Layers to Resolve Issues

MIMOMIMO

BeamBeamFormingForming NullingNulling

TopologyTopologyPlanningPlanning

SpectrumSpectrumPlanningPlanning

DeviceDeviceSpurs, …Spurs, …

RelocateAround

Spur

SpectrumToo Tight

Re-planAcross

Network

Re-planTopology

UnavoidableStrongSignal

NeedMore Range

Each Technology Can Throw “Tough” Situations to other More Suitable Technologies without Impact on User QOS

No Good MIMO Paths

Network-Wide

Radio Device

Link

Move to New Preselector

BandStrongStrong

NeighborNeighborSignalSignal

DynamicDynamicSpectrumSpectrum

Dynamic Spectrum Key to Adaptive

Networking

29

The DARPA WNAN Network & Radio

• Optimizing Layer– “Looks Through” Lower Layers to Make

Globally Optimizing Decisions• Topology Layer

– Makes the Network Topology Achievable by the Radios. Plans Network Around Spectrum, Power, Channel, …

• Network Layer– Multiple, Unique Networks Optimized for

Stream (Voice and Video), Broadcast (GBS-Like) and Packet Services

• MAC Layer– Adaptive Spectrum, MIMO, and

Beamforming Modes• PHY Layer

– Commercial Component-Based– Mitigated H/W Weaknesses – Standard RF Slice Widely Replicated

Global and LocalOptimizing

New WNANTechnology

New WNANTechnology

DynamicSpectrum

(XG)

MIMO(MnM)

COTS-Based Mil Radios

Existing Program Technology

New Program Technology

CBMANET(As

Applicable)

CBMANET(As

Applicable)

MEMS Filters and Sensors (MTO)

30

Hardware Platform

• Single RF Processing Slice Replicated to form 1, 2 and 4 channel MIMO/XG/ Beamforming Capable Radios

• Reverse of Standard ATO Approach– Build Early H/W and Incrementally Add Network

Capability– Have Early Demonstrator of DARPA Philosophy

and Technology

• Approach:– Develop early Prototypes By Leveraging

Available Commercial Chips (TV-Tuners and Others)

• Use Cost Pressure to Force Innovation for Lower Cost/Higher Performance

• Contribution from MTO New Analog Signal Processing (MEMs Filter Program) Essential

Frequency 900 MHz to 6 GHz

Power 36 dBw

SFDR 60 dB

IP3 What it is!

Peak 10 Mbps

Control- Based MANET

NewTechnology

NewTechnology

DynamicSpectrum

(XG)

MIMO(MnM)

COTS Chip Set

GPS Access Interleaved by Connectionless Networking

Digital Post Processing

$ 500 per 4 Channel Node, Spectrally Adaptive, MIMO, Beamforming, Member of Four Simultaneous Subnetworks, Ultra Low Latency

31

Conclusion

• Dynamic Spectrum Technology is: – Maturing– Being Tested and Demonstrated Now!– Being Worked into the Regulatory Process

• Fundamental Physics-based Constraints Limits Effectiveness of Frequency Assignment (Co-channel) Management in Dense RF Environments– May Offer Opportunity for Nearer Term Affordability and

Performance Benefits

• Need to Start Research into how to Best Exploit the Dynamics that Adaptive Spectrum Makes Possible– Not Clear that this is Evolutionary from Current Technology

• Dynamic Spectrum Access is the Key Technology Needed to Enable a New Generation of Low Cost, Adaptive Wireless Network Devices

32

Thank You!

Preston Marshallpreston.marshall @darpa.mil

Defense Advanced Research Projects AgencyAdvanced Technology Office

Connectionles

s

Connectionles

s

Networks

Networks

Radio-Isotope Micro-power

SourcesOne of

DARPA’s top 5 programs!

•Defense News, June 3, 2002

One of DARPA’s top 5

programs!

•Defense News, June 3, 2002

Wolfpack

Opinions expressed are those of the authors, and do not represent the position of DARPA, the Department of Defense, or the United States Government

PhotonicPhotonic

AvionicsAvionics

Retro-DirectiveNoise

CorrelatingRadar

RescueRadio

Adapt,Morph,

Proliferate

STORE

FORWARD

FLOODFLOODROUTEROUTE

STORE

FORWARD

FLOODFLOODROUTEROUTE