ITU Study Group 8
XG Communications Program
Information Briefing
Preston Marshall
DARPA ATO Program Manager
September 2004
DARPA XG Program
All Spectrum May Be Assigned, But…
XG is Developing the Technology
and System Concepts to
Dynamically Access Available
Spectrum
…Most Spectrum Is Unused!
Maximum Amplitudes
Amplidue (dBm)
Heavy Use
Heavy Use
Sparse Use
Medium Use
Frequency (MHz)
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Goal: Demonstrate Factor of 10
Increase in Spectrum Access
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XG Program Components
Measurements
Measurements
Policy
- Based
PolicyBased Controls
Controls
XG Products
Temporal, Spectral,
Dimensional, Energy
Characteristics
XG
XG Behaviors
Behaviors
Initial
Initial XG
XG Implementation
Implementation
Control of Features,
Priorities, Allocations,
Exclusions,…
Communications and
Sensor Applications
Transition to
User Community
The Primary Product XG Program is Not a New Radio, but a Set of
Advanced Technologies for Dynamic Spectrum Access
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XG Policy-Based Controls
• XG Being Developed In Advance of Policy Framework
– Implementations Must Fit With National And International
Regulations
– Algorithms Must be Adaptable
• Regional and operational situations
• Evolving policies
• Policy-Based “Metalanguage”
–
–
–
–
Translates Policy Rules Into Radio Behavior Controls
Decouples XG Technology From Regulatory Process
Control Operating Rules Based on Policies and Situations
Using Semantic Web Technologies (DAML/OIL/OWL)
Policy-Based Controls Will Draw on Practices & Methodologies
Currently Employed Manually by Spectrum Managers
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Top-Level Functional
Architecture
System
Policy
Sense
Radio
Platform
System
Strategy
Reasoner
Policy
Reasoner
Transmit
Device
Configuration
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Accredited
Policy
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Top-Level CONOPS
RF
Resource
Request
RF
Transmit
Plan
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Bound: Yes/No
Unbound: Binding
Constraints
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XG Key Principles
• Suitable for Range of Architectural Implementations
– Centralized and decentralized
• Identify “Interference-Preventing” Core Set
– Extensible to other features (subleasing, microcharging,...)
• Separate Policies From Engineering
– Avoid advocacy for specific spectrum sharing policies
– XG being developed In advance of Policy Frameworks
• Provide For Richness/Complexity of Policies
– Regulations neither flat nor hierarchical
• Allow For Diversity of Policy Sources
– Peer-Peer and hierarchical policy authorities
– Enable extension to “cognitive” optimizing logic
Policy “Layer” Flexible for Implementations to Use
Without Revisiting for Engineering & Policy Changes
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The XG Problem Space
How Do We?
Policy Language
Common
Approaches that
Must Be Agreed on,
and Can be Adopted
Widely
Abstract Capabilities (Behaviors)
Implementation
Design Specific
Approaches that Can
be Implemented in
Many Ways to
Develop Unique
Products
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Levels of Policy Regulation
Regional
National
Policy Authority
Gov’t
DoD
Services
Unit
Agencies
National
Non-Gov’t
Commercial & Civil
Owners
Unit User User User
User
User
Ontology-Based Policy Controls Enable Combining
and Processing Rules From Multiple Authorities
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Radio-Specific
Policies
Dimensions of Policy Definition
Network-Specific Policies
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XG Policy Language
• Need to Express Policies In A Way That The Radio Can Understand
– Current regulatory policies are implicit in radio hardware – policy and
technology are coupled and costly to change
– Need to be able to select and update policies in situ
• New locations, updated policies, new authorizations, ...
• Web Ontology Language (OWL) Being Used For Developing XG
Policy Language
– Basis for semantic web technology – W3C recommendation
– Provides structure and richness needed to express policies
– Includes general theorem proving/reasoning engines for deductive
inference
– OWL Is NOT Another Programming Language – structured way to build
representations of knowledge, facts, and rules/policies for machine
understanding
Technology Independent Mathematical Rigor and Logic
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Dimension 2
Technology and Policy
Evolution
1. Enhance Policy Flexibility by
Opening Up the Envelope
• Confidence Gained From
Experience
Operating
Operating
Area
Area
2. Increase Capability to
Dynamically Sense and Adapt
• Faster Spectrum Analyzers,
More Instantaneous
Bandwidth
3.
Develop Radios & Waveform
Standards that Can Exploit
Sharing Policies
• Wider Coverage, Better
Antennas, Adaptive
Waveforms
Dimension 1
XG Approach Allows the Operating Envelope To Autonomously Change
Over Time as Policies and Technologies Evolve Independently
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XG Policy Language Features
• Resolve Multiple Sources Of Policy Without Causing Failure
– Allows for Multiple Uncoordinated Sources of Policy
• Approachable Implementation
– Growing Community Of DAML/OWL Users, Features and Authoring Tools
• Class Extensible
– Maximizes Generality and Reduces Complexity
– Everyone Can Extend Policies To Their Needs
– Rapid Adoption Of New Policy Concepts And Technologies
• Provable Structure
– Set Theory, Logical Reasoning And Theorem Proving
• Host Implementation Independent
– All Policies Can Run On Any Compliant Device
Transition from Describing Self-Operation to Defining Effects on Others
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Community Input to XG
Protocol Development
• Based on Original ARPA/ Internet Protocol “Request for
Comment” Process
– Aspects of XG Standard that Implement Interference “Trust”
• Protocols, API’s, Behaviors, Certificates
– Not Design/Implementation Specific
• Web Sites Set Up to Host Draft Documents and Public
Discussions
–
–
–
–
Users Can Access and Comment on Drafts
RFC: http://www.darpa.mil/ato/programs/XG/rfcs.htm
Comments Accepted at [email protected]
List Server: http://list.ir.bbn.com/mailman/listinfo/xg-public
• Technical – Not Regulatory Process
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Accomplishments
• Collected RF Environment For Many Scenarios
– Data Being Used As Basis For Phase 2 Design Evaluations
• First Version Of Sensor Completed
– Provides Needed Capability For Rapid Wideband Sensing
– Next Revision To Explore High-Risk/High-Payoff Enhancements
• Three Feasible Designs For Interference Avoidance,
Network Operation, And Rendezvous
– Nearing Phase 2 Evaluations And Competition For Phase 3
Participation
• Policy Language And Radio Interface Defined
– Policy Language RFC v1 Composed And Released
– Extensible to Future “Cognitive” Technology
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Program Development Plan
FY02
FY03
FY04
FY05
FY06
Policy Language Development
System Integration
System Integration
XG System End-to-End
Mobile Demo
Sensing
High Risk Technologies
10X Reuse
Possible
Lab Demos
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10X Reuse
(Lab)
CDR
Final Demo
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