Transcript Dr. Larry Stotts

DoD Spectrum Symposium
14-15 October 2009
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
Network Centric Wireless Operations
Technical Challenges
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How do we enable networks to
scale to a large number of users
and adapt to users’ mobility?
How do we reliably deliver
information and sustain
networks despite frequent
network disruptions?
How do we provide reliable
spectrum access and
coexistence for thousands of RFbased systems?
How do we provide interoperability
and reliable networking among the
hundreds of US Military, Coalition, &
Public Safety radio types?
PRC 117
SATCOM
Cellular
How do we enable reliable
communications in urban areas
where signals are scattered by
buildings and terrain?
How do we provide content to
soldiers at an affordable cost?
Military
• MIL-STD
• 2 channels
• High Cost, Low Volume
• Voice & Data
COTS
Coalition
EPLRS
Public
Safety
•
•
•
•
JTRS GMR
Apple iPhone
Commercial Stds
Multi-channel
Low Cost
Rich User Content
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Why are These Challenges?
RADIO LIMITATIONS
NETWORK COMPENSATION
● Link Outages
● Disruption Tolerance
● LOS Routing
● LOS / NLOS Routing / Rerouting
● Bandwidth
● Spectral Re-Use and Routing
● Quality of Service (QoS)
● Prioritization / Retransmission
● Radio Command and Control
● Control Plane
● Dissemination to Disparate
Groups
● Multicast / Unicast
The Network May Overcome Radio Limitations
Next Generation (XG)
Technologies and System Concepts for Dynamic Spectrum Access
Goals
• Demonstrate Factor of 10 Increase in
Spectrum Access
• Demonstrate Enhanced Robustness by
Static Spectrum Management is Limited in
Its Ability to Improve Spectrum Utilization
Efficiencies – Currently ~ 6% Utilization
Interference Avoidance (Radios, Radar,
Jammers, etc.)
TODAY: Spectrum statically allocated
• Mechanism for “Bandwidth on Demand” thru
Dynamic Provisioning
XG Wideband Prototype
XG can operate across currently partitioned
spectrum allocations
XG Wideband Sensor
Capability to
Integrate
Software
with Existing
Legacy
Radios
PRC-148 PRC-152
JEM
Falcon-III
Frequency (MHz)
OBJECTIVE: Dynamically allocating
spectrum in frequency, space, and time
Unused
Spectrum
Changes in
Time and
Space
Time of Day (Sec)
90-95% not being used!
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XG/DSA Proven Potential
Field Upgrade
Capabilities Enhancement
Capabilities Proof
• Demonstrated
Core DSA
Operations
• Works, No Harm,
Adds Value
• Adaptive-Power NonInterference DSA Capabilities
• Policy-Based Spectrum Rule
Enforcement
Ready for Software
Upgrade to
Existing Inventory
• PRC-148 & -152
Handover to
Services
PRC-152
PRC-148
Networking
Aug06
Mar07
Mar08
Operational Exercise
• Demonstrated HighPower Non-Interference
DSA Capabilities in
Trident Warrior ‘07
Apr08
June08
Final Eval & Demo
• DSA-Enabled
PRC-148 & PRC-152
• CREW Coexistence
• Scalable DSA Networks
Transition to
Programs of
Record
• JTRS, WNW,
FCS…
WNaN
Low-Cost Edge
Communications
• JTRS, WNW,
FCS…
XG Wideband
Prototype
WNaN
XG/DSA Demonstrated Ability to be Implemented in Current and Future Network Systems
Mobile Networked MIMO (MNM)
Field Test Results
Exceeded All Program Goals
Metrics
Goals
Results
8 Node Network
Throughput
10
Mbps
16 Mbps
Spectral
Occupancy
10 MHz
7.8 MHz
LPD/AJ
Processing
20 dB
21dB
Latency
90%
< 2 sec
96-99%
Packet Delivery
80%
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
Exploiting the surrounding landscape to provide more robust, higher data rate
links that work well in complex urban environments
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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
Networking without Infrastructure
Reliable On-The-Move edge-to-edge
3.5x Increase in EPLRS capacity
Delivery in Disrupted Networks
3x bandwidth reduction for C2PC
using stateful compression
“Communications is the lifeblood of command / of a special forces team / of
intelligence/ of what we do...”
- from Report on “Coalition Operations in Operation Iraqi Freedom”, 27 Aug. 2007
Aggregate
Delivery: DTN
vice E2E IP
End-to-End IP
Only
in a permanently
partitioned network
DTN delivers
100% after
nominal latency
IP delivers
immediately or
never
DTN with IP
Per-Node
Delivery: DTN
vice E2E IP
in a permanently
partitioned network
Fort AP Hill Nov. 2007
IP doesn’t and can’t
deliver from
disconnected nodes
– 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.
TDMA/FDMA
 DIMA Technology Advancement
0 dB*
-3 dB*
Current method:
conventional
-6 dB*
signal 1
Digital Receivers
-9 dB*
signal 2
signal 3
signal 4
u
eq
cy
en
Fr
CSMA/CA
DIMA
Time
signal 1
signal 2
signal 3
signal 4
Multi-user based
algorithm
Time
Power
– 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
Time
802.11 Media Access Control (MAC) Protocol
Power
● Current State of Networking Technology
Power
DARPA Interference Multiple Access
(DIMA)
signal 1
signal 2
signal 3
signal 4
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
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