Spectrum coordination protocols and algorithms for cognitive radio networks

This thesis focuses on the problem of efficiently sharing spectrum resources in wireless networks through the use of appropriate spectrum etiquette protocols and related coordination algorithms. The performance of the proposed class of spectrum etiquette protocols is evaluated in various wireless network scenarios and compared with simpler reactive interference avoidance schemes. After validating its utility for coordination between existing wireless standards (such as IEEE 802.11/WiFi, Bluetooth, and 802.16/WiMax), the spectrum etiquette protocol is extended to serve as the foundation for a more complete adaptive wireless network where radio nodes may cooperate by forming or joining autonomous ad hoc clusters with multi-hop routing. A cognitive radio protocol stack is proposed for this scenario and validated using a combination of ns-2 simulations and experiments on the ORBIT radio grid testbed. The spectrum etiquette protocol proposed here is based on the Common Spectrum Coordination Channel (CSCC) approach which allows explicit coordination for spectrum usage among heterogeneous wireless radio nodes by announcement of their operation parameters such as frequency, power, rate, interference, etiquette policies, etc. An experimental proof-of-concept protocol evaluation is conducted to examine interoperability between WiFi and Bluetooth networks, demonstrating significant performance gains with CSCC as compared to the case with no coordination. Simpler reactive interference avoidance schemes in which radio nodes adjust their transmit parameters such as frequency, power and transmission time based on local observations are also examined in more detail for comparison with CSCC. In particular, we present a detailed comparison between reactive algorithms and proactive CSCC-based etiquette for a co-existence scenario in which both 802.11b and 802.16a operate in the same shared spectrum. With a higher level of spectrum coordination complexity, we examine the ad hoc collaboration scenario in which radio nodes may cooperate with each other to form so-called adaptive wireless networks with multi-hop routing. The CSCC protocol provides a reasonable foundation for this scenario as well by serving as a bootstrapping and resource coordination protocol for radios involved in ad hoc collaboration. Using the CSCC as a base, we propose a complete cognitive radio protocol stack which includes bootstrapping, network/service discovery, cross-layer routing and name/address translation. Each protocol component is validated using a combination of ORBIT experiments and ns-2 simulations.Ph.D.Includes bibliographical references (p. 101-105)