Title page for ETD etd-090809-120824

Document Type thesis

Author Name Bobrowski, Kevin Matthew

URN etd-090809-120824

Title Practical Implementation Considerations for Spectrally Agile Waveforms in Cognitive Radio

Degree ME

Department Electrical & Computer Engineering

Advisors
Professor Alexander M. Wyglinski, Advisor
Professor Xinming Huang, Committee Member
Professor Donald Richard Brown, Committee Member

Keywords
NC-OFDM
cognitive radio
OFDM
software defined radio

Date of Presentation/Defense 2009-09-08

Availability unrestricted

Abstract
As the demand for bandwidth increases, the inefficient use of the spectrum becomes more apparent and limiting. Currently, secondary (unlicensed) users can not use sparsely occupied portions of radio spectrum that are not allocated to them. In prior research, a variant of Orthogonal Frequency Division Multiplex (OFDM) called Non-Contiguous OFDM (NC-OFDM) was found to be a suitable transmission technique for enabling Dynamic Spectrum Access, which allows for multiple secondary users to share the spectrum. This thesis presents an algorithm for the synchronization of NC-OFDM. Moreover, a hardware architecture is proposed for the synchronization, and a pruned FFT/IFFT core is designed.

At present, there has been minimal research into synchronization for NC-OFDM systems. As with any modulation scheme, synchronization is an important part for receiving the transmission successfully. The current synchronization scheme is simulated in variety of wireless channels to show that it can successfully communicate in the tested channels.

Additionally a hardware architecture is laid out for the practical implementation of the synchronization algorithm. Since NC-OFDM does not use all of the carriers for transmission, the FFT and IFFT can have their computations reduced. Since the FFT and IFFT are important parts to the receiver and the transmitter, a pruned FFT/IFFT in hardware makes the most sense to be able to reduced the computation. The number of butterfly computations is reduced at the expense of a large increase in resource usage.

Files
bobrowksi.pdf

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Document Type	thesis
Author Name	Bobrowski, Kevin Matthew
URN	etd-090809-120824
Title	Practical Implementation Considerations for Spectrally Agile Waveforms in Cognitive Radio
Degree	ME
Department	Electrical & Computer Engineering
Advisors	Professor Alexander M. Wyglinski, Advisor Professor Xinming Huang, Committee Member Professor Donald Richard Brown, Committee Member
Keywords	NC-OFDM cognitive radio OFDM software defined radio
Date of Presentation/Defense	2009-09-08
Availability	unrestricted
Abstract As the demand for bandwidth increases, the inefficient use of the spectrum becomes more apparent and limiting. Currently, secondary (unlicensed) users can not use sparsely occupied portions of radio spectrum that are not allocated to them. In prior research, a variant of Orthogonal Frequency Division Multiplex (OFDM) called Non-Contiguous OFDM (NC-OFDM) was found to be a suitable transmission technique for enabling Dynamic Spectrum Access, which allows for multiple secondary users to share the spectrum. This thesis presents an algorithm for the synchronization of NC-OFDM. Moreover, a hardware architecture is proposed for the synchronization, and a pruned FFT/IFFT core is designed. At present, there has been minimal research into synchronization for NC-OFDM systems. As with any modulation scheme, synchronization is an important part for receiving the transmission successfully. The current synchronization scheme is simulated in variety of wireless channels to show that it can successfully communicate in the tested channels. Additionally a hardware architecture is laid out for the practical implementation of the synchronization algorithm. Since NC-OFDM does not use all of the carriers for transmission, the FFT and IFFT can have their computations reduced. Since the FFT and IFFT are important parts to the receiver and the transmitter, a pruned FFT/IFFT in hardware makes the most sense to be able to reduced the computation. The number of butterfly computations is reduced at the expense of a large increase in resource usage.
Files	bobrowksi.pdf