2. Ensuring Capabilities Via Spectrum Access: Meeting the 21st Century Mission Dr. Larry B. Stotts Deputy Director, Strategic Technology Office Defense Advanced Research Projects Agency Ensuring Capabilities Via Spectrum Access: Meeting the 21st Century Mission Dr. Larry B. Stotts Deputy Director, Strategic Technology Office Defense Advanced Research Projects Agency The views, opinions, and/or findings contained in this article/presentation are those of the author/presenter and should not be interpreted as representing the official views or policies, either expressed or implied, of the Defense Advanced Research Projects Agency or the Department of Defense Approved for Public Release, Distribution Unlimited DoD Spectrum Symposium 14-15 October 2009

3. 2 Network Centric Wireless Operations Technical Challenges 2 JTRS GMR Apple iPhone How do we enable networks to scale to a large number of users and adapt to users’ mobility? How do we provide reliable spectrum access and coexistence for thousands of RF- based systems? How do we reliably deliver information and sustain networks despite frequent network disruptions? How do we enable reliable communications in urban areas where signals are scattered by buildings and terrain? How do we provide interoperability and reliable networking among the hundreds of US Military, Coalition, & Public Safety radio types? How do we provide content to soldiers at an affordable cost? COTS Military MIL-STD 2 channels High Cost, Low Volume Voice & Data Commercial Stds Multi-channel Low Cost Rich User Content PRC 117 Coalition EPLRS Public Safety Cellular SATCOM

4. The Network May Overcome Radio Limitations RADIO LIMITATIONS ●Link Outages ●LOS Routing ●Bandwidth ●Quality of Service (QoS) ●Radio Command and Control ●Dissemination to Disparate Groups NETWORK COMPENSATION ●Disruption Tolerance ●LOS / NLOS Routing / Rerouting ●Spectral Re-Use and Routing ●Prioritization / Retransmission ●Control Plane ●Multicast / Unicast Why are These Challenges?

5. XG Wideband Sensor 4 Next Generation (XG) Technologies and System Concepts for Dynamic Spectrum Access Static Spectrum Management is Limited in Its Ability to Improve Spectrum Utilization Efficiencies – Currently ~ 6% Utilization OBJECTIVE: Dynamically allocating spectrum in frequency, space, and time Frequency (MHz) Time of Day (Sec) Unused Spectrum Changes in Time and Space 90-95% not being used! Goals Demonstrate Factor of 10 Increase in Spectrum Access Demonstrate Enhanced Robustness by Interference Avoidance (Radios, Radar, Jammers, etc.) Mechanism for “Bandwidth on Demand” thru Dynamic Provisioning TODAY: Spectrum statically allocated XG can operate across currently partitioned spectrum allocations PRC-152 Falcon-III PRC-148 JEM Capability to Integrate Software with Existing Legacy Radios XG Wideband Prototype

6. XG/DSA Proven Potential PRC-152 PRC-148 XG Wideband Prototype WNaN XG/DSA Demonstrated Ability to be Implemented in Current and Future Network Systems

7. Mobile Networked MIMO (MNM) 6 Exploiting the surrounding landscape to provide more robust, higher data rate links that work well in complex urban environments MetricsGoalsResults 8 Node Network Throughput 10 Mbps 16 Mbps Spectral Occupancy 10 MHz7.8 MHz LPD/AJ Processing 20 dB21dB Latency90% < 2 sec 96-99% Packet Delivery80%90-96% 8 Node Network Initialization Time < 10 min < 1 min Node Entry Time< 2 min< 3 seconds Detect Node Exit Time < 30 sec < 3 seconds Field Test Results Exceeded All Program Goals

8. Disruption Tolerant Networking Reliable Communications Across Intermittent and Disrupted Tactical Networks DTN is developing network protocols and interfaces to provide high reliability communications over intermittent and disrupted links Better reliability in service scenarios Reliable On-The-Move edge-to-edge Delivery in Disrupted Networks DTN delivers 100% after nominal latency IP delivers immediately or never End-to-End IP Only DTN with IP IP doesn’t and can’t deliver from disconnected nodes Aggregate Delivery: DTN vice E2E IP in a permanently partitioned network Per-Node Delivery: DTN vice E2E IP in a permanently partitioned network Fort AP Hill Nov. 2007 - from Report on “Coalition Operations in Operation Iraqi Freedom”, 27 Aug. 2007 “Communications is the lifeblood of command / of a special forces team / of intelligence/ of what we do...” Networking without Infrastructure 3.5x Increase in EPLRS capacity 3x bandwidth reduction for C2PC using stateful compression

9. DARPA Interference Multiple Access (DIMA) ●Current State of Networking Technology –Current communication networks use the interference avoidance paradigm, which fundamentally limits overall network performance, i.e. network capacity and user throughput. –Interference avoidance relies on spectrum allocation methods that limits users to partial use of the spectrum and require a controlling entity to manage channel access. 8 8 Power Time Frequency TDMA/FDMA Power Time Frequency Demonstrate a mobile ad hoc spread spectrum communications network that requires no infrastructure and has 3X the aggregate capacity of 802.11 or IS-95  DIMA Technology Advancement – Exploit multi-access interference through Multiuser Detection (MUD) allowing multiple users to simultaneously occupy the same channel. – Enables high capacity mobile ad-hoc spread spectrum communications without infrastructure or power control 802.11 Media Access Control (MAC) Protocol DIMA signal 4 signal 1 signal 2 signal 3 0 dB* -3 dB* -6 dB* -9 dB* Current method: conventional Multi-user based algorithm Digital Receivers signal 1 signal 2 signal 3 signal 4 signal 1 signal 2 signal 3 signal 4