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Dissertation Defense

Enhancing Coexistence, Quality of Service, and Energy Performance in Dynamic Spectrum Access Networks

Ashwini Kumar

Dynamic Spectrum Access (DSA) is an upcoming wireless technology

with the potential to alleviate spectrum-usage inefficiency from the

current static spectrum allocation model of wireless communication.

However, DSA technology is still in its infancy. There are several

technical challenges in achieving effective DSA. This research work

identifies problems associated with existing DSA schemes along three

key dimensions—coexistence, quality of service (QoS), and energy.

This thesis proposes novel and practical system-oriented solutions in

order to address the identified shortcomings with traditional DSA.

“Awareness-cum-adaption” is the central theme across the proposed

methods. First, the thesis focuses on the generic DSA coexistence problem.

It presents a dual-mode DSA operation scheme featuring joint sensing and

transmission scheduling in order to enable safe and efficient

time-domain incumbent-unlicensed coexistence on a licensed channel.

A prototype called Spectrum-Conscious WiFi (SpeCWiFi), is also

developed. Second, it provides important insights into the QoS impact

of DSA through the case-study of a consumer DSA-based wireless

network. Third, it presents the Context-Aware Spectrum Agility

(CASA) optimization strategy, to address the DSA's QoS issues from a

device-centric perspective. Fourth, to tackle the QoS problems at the

network level, it proposes a network service framework called DSA

Synchronization (DSASync). DSASync consists of algorithms based on

buffering and traffic-shaping to effectively manage end-to-end

connections in DSA networks. Finally, this thesis explores the

energy cost of DSA through an empirical analysis, and proposes the

Dynamic Energy Management for DSA (DEMD) scheme to reduce its

energy footprint.

Sponsored by

Kang G. Shin