| Once a novelty enjoyed by few, wireless communication has quickly become a necessity for many in today's rapidly-paced mobile world. Future fourth generation (4G) communication systems aim to fuse cellular and internet capabilities into a single operating environment, efficiently providing universal, high-speed access for civilian and military communicators alike. One potential key to 4G implementation is software defined radio (SDR) technology, which enables adaptive signal generation This adaptivity inherently provides waveform diversity which may ultimately be controlled through cognitive radio (CR) principles, i.e., by actively monitoring channel conditions, traffic loads, spectrum availability, etc., while tailoring waveform features to improve overall efficiency. The synergistic union of SDR control via CR principles is called CR-based SDR. Although research is rapidly progressing in SDR hardware and software venues, current SDR research lacks the theoretical foundation and analytic framework to fuse these developments together to permit efficient development, characterization, and implementation.; This research addresses this deficiency by providing a general analytic framework for analyzing, characterizing, and implementing spectrally modulated, spectrally encoded (SMSE) signals within CR-based SDR architectures. Researchers agree that orthogonal frequency division multiplexing (OFDM) will be the bedrock modulation and multiplexing technique for 4G systems given it provides unique advantages for communicating in fading environments. In this work, OFDM-based signals are collectively classified as SMSE given that data modulation and encoding are both applied in the spectral domain. The proposed analytic framework, developed around six key waveform design variables, provides the desired analytic commonality and unification for a myriad of SMSE signals.; SMSE framework applicability and adaptivity are shown using specific waveform design variable instantiations to generate analytic expressions for seven candidate 4G signals. The resultant expressions are compared with published results and consistency established for all signals considered. Next, framework implementation is demonstrated via modeling and simulation to reinforce practical utility. It is shown that expected communication performance is maintained within various SMSE coexistence scenarios, i.e., scenarios containing multipath fading, multiple access interference, and partial band interference. Simulated bit error performance for various signals constructed within the unifying SMSE framework is shown to correlate well with theoretical predictions. |
