Protocol Design and Performance Issues in Cognitive Radio Networks

Abstract

A cognitive radio is a frequency agile wireless communication device based on software defined radio that enables dynamic spectrum access. cognitive radio represents a significant paradigm change in spectrum regulation and usage, from exclusive use by licensed users (or, primary users) to dynamic spectrum access by secondary users. While considerable progress is made in understanding the physical layer aspects of cognitive radio and on developing effective dynamic spectrum access schemes, it is now imperative to study how the enhanced spectrum usage can effect or benefit the upper layers, such as medium access, network and transport layers. In this dissertation, some of the important issues related to the implementation of Cognitive Radio Networks and their performance modeling are studied. Firstly, the common control channel problem is discussed and three network setup mechanisms are proposed which do not require a common control channel. Secondly, selective broadcasting technique is proposed to improve the communication effeciency of Multi-Hop Cognitive Radio Networks, Thirdly, the capacity of secondary users in terms of blocking probability for varying dynamic spectrum access network parameters is studied. Based on the study of the capacity of secondary users, the effect of dynamic spectrum access on Transport Control Protocol Performance is modeled. Finally, to ensure cooperative spectrum sensing, we design a cross-layer game to attain Nash Equilibrium at mutual cooperation. All of these ideas have been either simulated or mathematically proven to have better performance than the existing models.