Title page for ETD etd-05082010-161920

Type of Document Master's Thesis
Author Deshpande, Amol Anant
Author's Email Address amoldesh@vt.edu
URN etd-05082010-161920
Title Policy Reasoning for Spectrum Agile Radios
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Park, Jung-Min Jerry Committee Chair
Bose, Tamal Committee Member
Hsiao, Michael S. Committee Member
  • Spectrum Access Policies
  • Policy Reasoning
  • Cognitive Radios
Date of Defense 2010-05-04
Availability unrestricted
DARPA’s neXt Generation (XG) communication program proposes the use of Dynamic Spectrum

Access (DSA) wherein intelligent radios can realize opportunistic usage of frequency

bands by identifying the under-utilized spectrum and reasoning about it. Implementing such

a flexible scheme requires changes in the current static spectrum management approach. As

a result, declarative spectrum management through policy-based dynamic spectrum access

has garnered significant attention recently.

Policy-based dynamic spectrum access decouples the Spectrum Access Policies and Policy

Processing Components from the Radio Platform. The Policies define conditions under which

the radios are allowed to transmit in terms of frequencies used, geographic locations, time etc.

The Policy Processing Components include a reasoning engine called the Policy Reasoner,

which is responsible for enforcing these policies.

This thesis describes the design and implementation of a novel policy reasoner called Bi-

nary Decision Diagram based Reasoner for processing Spectrum Access Policies (BRESAP).

BRESAP processes spectrum policies efficiently by reframing the policy reasoning problem

as a graph based Boolean function manipulation problem. BRESAP uses Binary Decision

Diagrams (BDDs) to represent, analyze and process the policies. It uses a set of efficient

graph-theoretic algorithms to merge these policies into a single meta-policy and compute

opportunity constraints.

Our policy reasoner has the capability to respond to invalid and under-specified transmission

requests sent by the System Strategy Reasoner (SSR). In case of invalid or under-specified

transmission requests, BRESAP returns a set of opportunity constraints which inform the

SSR of the changes needed to the transmission parameters in order to make them conform

to the policies. We also propose three algorithms for computing the opportunity constraints.

The complexity of the first algorithm is proportional to the number of variables in the metapolicy

BDD, while the complexities of the second and third algorithms are proportional to

sum of number of variables and the size (i.e., number of nodes) of the meta-policy BDD.

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