Power Control Algorithm For Cognitive Radio Networks

Cognitive radio technology is considered as the"Next Big Thing"in the future wireless communication field. It needs deepresearch in a variety of areas, among which, power control in cognitive radio network is a widely-discussed key technique.From the perspective of characteristic in cognitive radio, this thesis develops a deep research on power control in cognitive radio networks. This thesis tracks the most recent direction of studies on power control in cognitive radio networks and makes a thorough analysis on the algorithm design, while summarizing their pros and cons. A full and detailed instruction is given regarding the effects of different network architecture (centralized, distributed and hybrid networks) on design of power control algorithms, which also leads to the principle of designing power control algorithms in different network architecture. Besides, three power control schemes, which are applied effectively under different network architecture, are proposed and well described in this thesis, from the intention to the specific parameter configuration. The performances of the schemes are proved and examined by mathematic analysis and computer simulation.Chapter 1 investigates background and significance of researching on cognitive radio, reviews and summarizes current research on cognitive radio. Requirements for power control in cognitive radio networks and the challenges it faces are elaborated in this chapter, by which, the significance of power control in cognitive radio networks is indicated.Chapter 2 proposes a two-step channel and power allocation scheme in centralized cognitive networks based on Fairness with lower complexity. Theoretical analysis show that the proposed scheme can protect licensed users from harmful interference while support cognitive radio users'quality of service (QoS). Besides, Simulation results indicate that the proposed scheme can also guarantee low power consumption and fair resource allocation.Chapter 3 designs distributed power control scheme based on game theory. By analyzing geometric characteristics of utility function, the proposed scheme can protect licensed users from harmful interference while satisfy different QoS requirements as well as guarantee power convergence. In addition, to make the proposed distributed algorithm practical, corresponding distributed power control protocol is also designed for the proposed scheme. Simulation results examine the above properties and show the performance in improving spectrum efficiency of the proposed distributed power control scheme.Chapter 4 discusses power control problem in hybrid cognitive radio network. After introducing the idea and characteristics of the cognitive radio based Hierarchical Spectrum Sharing Network (HSSN), which is designed by National key lab of communications of University of Electronic Science and Technology of China, a hybrid power control scheme is proposed for this network.Chapter 5 summarizes this thesis and points out the future research direction and the next step of work for the design of power control algorithms in cognitive radio networks.