Interference-aware resource management techniques for cognitive radio networks

The proliferation of wireless services and devices has led to a shortage of available spectrum. However, recent spectrum measurements have revealed that some spectrum bands are continuously occupied, while others are occupied only a fraction of the time. Recently, Cognitive radio (CR) systems have been proposed as a method for improving spectrum utilization. By employing spectrum-sensing and dynamic spectrum-access techniques, CR users continuously detect the presence or absence of the primary users (PUs) and dynamically access vacant spectrum subbands without causing excessive interference to the PUs. The objective of the proposed research is to develop interference-aware resource management techniques for CR networks that opportunistically operate within the licensed primary networks spectrum and to investigate the application of such CR techniques to emerging wireless communication systems.;To study the effects of CR interference on PUs transmission, we undertook a set of laboratory experiments to analyze the interference between a CR system represented by a recently introduced CR standard, known as the wireless regional-area network (WRAN) standard, and a primary system represented by digital television (DTV) transmission. Through these experiments, we determined the tolerable levels of WRAN interference into DTV receivers and studied the effect of these interference levels on WRAN deployment.;Based on the need for efficient utilization of the primary network spectrum, we devised efficient interference-aware radio resource allocation (RRA) techniques for orthogonal frequency-division multiple access (OFDMA) CR networks. These RRA techniques aim to maximize the CR network throughput and to keep the CR interference to the primary network at or below a predefined threshold, known as the "interference temperature" threshold.;Both the amount of interference introduced into the PUs subbands by the CR network and the achievable CR network throughput depend on the efficiency of the employed spectrum-sensing algorithm. In this thesis, we propose a joint spectrum-sensing design and power control algorithm that lead to increased CR network throughput and efficient protection of the PUs from undue interference.;Interference coordination (IC) is considered a key technique for throughput maximization in emerging heterogeneous wireless networks such as long term evolution (LTE) networks. We propose a CR-based IC and RRA algorithm for OFDMA femtocell deployments to achieve efficient spectrum utilization and maximum network throughput.;CR is envisioned as a key enabling technology for future wireless networks; our novel CR techniques will provide other researchers useful tools to design and deploy such networks.