Grand Challenges in Achieving Dynamic Spectrum Access

1. 2006 Technology and Policy for Advanced Spectrum Rescue Radio Polarization Modulation Rotation Photonic Avionics Wolfpack Connectionless Networks • One of DARPA’s top 5 programs! • Defense News, June 3, 2002 Radio-Isotope Micro-power Sources Exploiting Grand Challenges in Achieving Dynamic Spectrum Access Adapt, Morph, Proliferate Wireless Network After Next Preston Marshall preston.marshall @darpa.mil Defense Advanced Research Projects Agency Advanced Technology Office Opinions expressed are those of the authors, and do not represent the position of DARPA, the Department of Defense, or the United States Government

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 Equivalent Wired 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 Enter Search Infrastructureless Networking:How Do I Network Without? Cell Towers Unlimited Energy Central Servers Frequency & Network Planning Known Topology Cache Servers Index Services Fiber & Wires

6. Technology Implications

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. DARPA XG Program All Spectrum May Be Assigned, But… XG is Developing the Technology and System Concepts for DoD to Dynamically Access All Available Spectrum …Most Spectrum Is Unused! Goal: Demonstrate Factor of 10 Increase in Spectrum Access

11. DARPA XG Program Investments Signal Processing Algorithms Sensor Technology Distributed Sensing Algorithms Subnoise Detection Spectrum Measurements Capability and Affordability Increased Awareness Spectrum Awareness Dynamics Optimizing Strategies Tactics Interference Effects Assessment Adaptive NetworkOperation XG Prototype & Demonstration Assessments Non-Interfering Operation Performance Experiments Spectrum Adaptive Networking Engineering Basis Behavior Enforcement Implementation PolicyLanguage Methodology Policy Reasoning Framework &Semantics Policy Description IEEE 1900

12. Sensing Loop Policy Reasoner RF Info Acquisition Develop Options Process Request System Strategy Reasoner Determine Opportunities Select Opportunities Accredited Policy Engine Policy Transceiver XG Operation MessageFlow RF Resource Request Radio Platform RF Transmit Plan Yes/No or Additional Constraints

13. What We Expect • Simulation of Early Designs Using Recorded Spectrum Measurements Shows Significant Potential

14. XG Prototype Developmentand Demonstration Schedule Phase Phase Phase 3b Phase 3b Phase 3c Phase 3c Task Name Task Name 3a 3a Demonstrations Demonstrations #3 adds: #3 adds: Criteria Criteria Dev’t Dev’t 6 mobile nodes 6 mobile nodes 1 1 1. Two Node 1. Two Node #5 adds: #5 adds: Network Functions Network Functions 2. Five Node 2. Six Node 2 2 25 mobile nodes 25 mobile nodes Low Power Detector Low Power Detector 3 3 3. Technology 3. Technology Enhanced Detector Enhanced Detector 4 4 4. Initial System 4. Initial System 5 5 5. Upgraded System 5. Upgraded System #1 demonstrates: #1 demonstrates: 6 6 6. Final Configuration 6. Final Configuration 2 nodes 2 nodes #2 adds: #2 adds: 7 7 #4 adds: #4 adds: 7. Final Urban 7. Final Urban Demo Spectrum Policy Demo Spectrum Policy 6 nodes 6 nodes Policy Enforcer Policy Enforcer 8 8 8. Final Test Range 8. Final Test Range Performance Detector Performance Detector Group Behaviors Group Behaviors Ultimate Modem Ultimate Modem Rendezvous Rendezvous # 6, 7, & 8 Demonstrate # 6, 7, & 8 Demonstrates Frequency Selection Frequency Selection All Technologies All Technologies XG 008 v6 XG 008 v6 • 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

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. NC DoD Radio (fixed) XG Radios (mobile) Equipment Installed in Vans NC DoD Radio and Test Equipment XG Radio and Test Equipment Legacy Radio Link XG Link

17. XG Behaves!! Without XG – Signals Collide With XG – Sense and Jump With XG -- Moved Before Interfering

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. Bit Error Rate With XG Typical impulsive Environmental Noise Bit Error Rate XG Node Interferes within 600 meters Node Separation (mtrs) Scenario Time Simple Scenario, With and Without XGMilitary PSC-5 FM Radio Victim Victim Radio Bit Error Rate Without XG XG Caused Noise Bit Error Rate Only Background Impulsive Noise Node Separation (mtrs) Scenario Time

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

21. 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) Policy Compliant Behavior

22. Future Cognitive Components Will Not Come From Just One Source Spectrum Policy Country #1 Network Service #1 Persistence Policy Spectrum Policy Country #2 Network Service #2 Topology Optimizing Spectrum Leasing Policy Multiple Dynamically Interacting Cognitive Processes Network Optimizing Enterprise 1 Policies Security Mode Enterprise 2 Policies Security Mode Interoperable Mode # 4 Interoperable Mode # 2 Interoperable Mode # 3 Device Mfr. Constraints Industry Standard A Interoperable Mode # 1 Industry Standard B Industry Standard C

23. XG Program – Transition • 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 (WidespreadNIB 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 Military on Military Coordinated Sharing Opportunistic Spectrum Not Necessary to Establish New Regulatory Framework, Either Nationally or Internationally

24. Post-RF Preprocessing Non-Linear Distortions Noise Floor Increases 20 dB! Results Shown for 10w, 10dB Gain, IIP3 = 50dBm (Ultra High Quality) LNA w/ Prime Pwr > 12 Watts DARPA Tuner Study Conclusion INPUT SIGNAL • 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 Spectrum Appears to Offer Lots of Opportunities Even Dynamic Spectrum Can Not Help the Radio with 20 db of Intermod!!

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 IIP3 > 20dBm Required to Avoid 50% of Spectrum Having 5 dB Intermod Noise But,… Even 20 dBm of IIP3 requires at least 5 watts of Prime Power (Ideally)

26. DARPA Director’s Vision of Communications Technology Evolution Key to Infrastructureless Comm MEMS/NEMS Self-Forming Mobile Small Unit Operations-Situational Awareness System Program– SUO SAS Mobile Networked MIMO Program – MNM Future Combat System – Comms Program - FCS-C Future Networks Packet Radios Dynamic Spectrum Global Mobile Program - GLOMO Next Generation Comms Program - XG Wireless Network after Next Program - WNAN Topology Optimizer Control-Based Mobile Ad-Hoc Networking Program - CBMANET Cognitive Technology Information Protection Dynamic Quarantine of Computer Based Worm Attacks Program – DQW Defense Against Cyber Attack in MANETs Program – DCMANET

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 Each Technology Can Throw “Tough” Situations to other More Suitable Technologies without Impact on User QOS Topology Planning Re-plan Topology Spectrum Planning Re-plan Across Network Network-Wide MIMO Spectrum Too Tight Dynamic Spectrum Key to Adaptive Networking No Good MIMO Paths Dynamic Spectrum Need More Range Relocate Around Spur Radio Device Unavoidable Strong Signal Move to New Preselector Band Device Spurs, … Beam Forming Nulling Strong Neighbor Signal Link

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 Local Optimizing CBMANET (As Applicable) New WNAN Technology CBMANET (As Applicable) New WNAN Technology Dynamic Spectrum (XG) MIMO (MnM) COTS-Based Mil Radios MEMS Filters and Sensors (MTO) New Program Technology Existing Program Technology

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 GPS Access Interleaved by Connectionless Networking Digital Post Processing Control - Based MANET New Technology New Technology Dynamic MIMO $ 500 per 4 Channel Node, Spectrally Adaptive, MIMO, Beamforming, Member of Four Simultaneous Subnetworks, Ultra Low Latency Spectrum (MnM) (XG) COTS Chip Set

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. Rescue Radio Polarization Modulation Rotation Photonic Avionics Wolfpack Connectionless Networks • One of DARPA’s top 5 programs! • Defense News, June 3, 2002 Radio-Isotope Micro-power Sources Thank You! Adapt, Morph, Proliferate Wireless Network After Next Preston Marshall preston.marshall @darpa.mil Defense Advanced Research Projects Agency Advanced Technology Office Opinions expressed are those of the authors, and do not represent the position of DARPA, the Department of Defense, or the United States Government