| The demand for wireless services is on the rise and the vast majority of the spectral resources have already been licensed. Consequently, cognitive radio technology has been proposed to make secondary use of licensed spectrum. Multi-carrier communication technology has been suggested to utilize the white spaces in the spectrum. Orthogonal frequency-division multiplexing (OFDM) was the first multicarrier technique proposed for cognitive radios. However, OFDM suffers from significant leakage among the carriers of different users. On the other hand, filterbank multicarrier (FBMC) communication can overcome the spectral leakage. Therefore. FBMC has been suggested as an alternative to OFDM for cognitive radios. In this dissertation, we investigate the implementation issues that need to be addressed for an actual deployment of FBMC.A preamble design and related algorithms are proposed for FBMC systems. The proposed preamble is used to detect the beginning of packet, to adjust an automatic gain control, to synchronize the carrier frequency and timing phase, and to identify the channel impulse response. Furthermore, decision directed carrier and timing tracking algorithms are proposed to track residual tinting and carrier offset after the acquisition. In addition, a decision directed phase lock loop (PLL) is designed to force any built up phase error to zero. Also, an algorithm is implemented to track the best timing phase by minimizing a cost function.This dissertation also reports implementation of a cognitive radio equipped with filterbank spectrum sensing. The cognitive radio was implemented on a software defined radio platform. The filterbank spectrum sensor is shown to exhibit superior performance in terms of the spectral dynamic range when compared to the FFT based techniques. The radio can detect the presence of interferers on the carrier that is currently using and move to an unoccupied part of the spectrum.FBMC is also applied to fault detection on live wires. Optimally designed synthesis filterbanks are used to confine the test signal to the portion(s) of the frequency band that are free of live signal. Moreover, optimal analysis filters are designed which can separate the reflected test tones and minimize leakage from the live wire signals.Efficient polyphase structures for implementation of FBMC are investigated. A novel formulation for a family of polyphase structures for staggered modulated multitone (SMT) is derived Using our derivation, it is shown that some of the SMT analysis structures in the literature are not applicable to frequency selective channels. |
