A frequency agile transmitter design for cognitive radio applications in the TV band -

Abstract

With the growth of mobile data applications and the development of communication systems, the spectrum is becoming very scarce. To ease congestion and boost speeds, cognitive radio (CR) is currently seen as a major solution. It is expected to be the key player in the new wireless technologies. It is one of the most capable techniques to efficiently utilize the spectrum and intelligently share the wireless resources. In a CR network, unlicensed users (secondary users) are allowed to access spectrum bands licensed to primary users, while avoiding interference with them. One of the main motivating factors attributing to the growth of work in CR is the current worldwide digital transition of the TV broadcasting band which resulted in abundant of vacant spectrum. TV white spaces (TVWS) refer to these unused portions of the spectrum in the TV band. These unused TV white spaces are an attractive target for cognitive radio applications, since they operate at an easy to use frequency, and have good propagation characteristics, improved communication quality, better building penetration, and lower energy consumption. A radio front-end transmitter is a complete system used to transmit radio signals on a certain carrier frequency. In cognitive radio, there is an important need for reconfigurable Radio Frequency (RF) front end transmitter that can be set to steer to any band and tune to a channel of any bandwidth. The main challenge in building this transmitter is the ability in designing linear and spectrally-agile components and architectures. This is because cognitive radio transmitters are required to operate in any unoccupied channel of the frequency range. In this dissertation, an RF front-end design for frequency-agile transmitter for cognitive radio system applications in the TV band is investigated. The transmitting antenna and the broadband power amplifier are completely examined, in order to come up with developed designs suitable for several cognitive radio applications in the TV band. Concerning the transmitti