Research Challenges in Dynamic Spectrum Access

1
Research Challenges in Dynamic Spectrum Access
Luiz DaSilva Wireless _at_ Virginia Tech

• Defense Spectrum Summit
• Annapolis, MD December 7, 2006

2
Broad Questions

• How do radios achieve awareness of the current
  spectrum utilization?
• Cooperative spectrum sensing
• How do radios adapt to a dynamic environment to
  opportunistically take advantage of available
  spectrum?
• Cognitive radios and cognitive networks

3
The commercial world has already started dealing
with these challenges

• IEEE 802.22 refarming of VHF/UHF TV bands
  cognitive Regional Area Network MAC
• IEEE 802.11h dynamic frequency selection and
  transmit power control
• IEEE 802.11y amendments to 802.11 for
  operation in 3.65-3.7 GHz band standardized
  interference avoidance mechanism
• IEEE 802.16h license-exempt operation of
  802.16 cognitive WiMax (?)

4
Cooperative Spectrum Sensing

• Research tasks
• Design digital signal processing methods at the
  node level
• Develop data fusion techniques
• Exchange information among radios (how much is
  enough?)
• Evaluate complexity and reliability of sensing
  stage

Source Dr. Claudio da Silva, Virginia Tech
5
Cognitive Radios

• How cognitive?
• Development of the cognitive engine
• Hard vs. soft AI
• Biologically inspired techniques
• How do we agree on a set of rules that ensures
  stability, fairness, efficiency?
• Policy
• Economic incentives
• Game theory

Source Dr. Charles Bostian, Virginia Tech
6
Cognitive Networks

• We are developing cognitive networks, capable of
  perceiving current network conditions and then
  planning, learning, and acting according to
  end-to-end goals.
• Issues include stability, fairness, efficiency of
  spectrum allocation

Read more R. Thomas et al., Cognitive networks
adaptation and learning to achieve end-to-end
performance objectives, IEEE Communications
Magazine, Dec. 2006
7
For more information
Wireless _at_ Virginia Tech http//www.wireless.vt.e
du
Luiz DaSilva (ldasilva_at_vt.edu) Voice
1-703-387-6039 www.lan.ece.vt.edu