This article gives a brief tutorial on transform-domain communication system (TDCS), OFDM, and MC-CDMA. The primary goal of this article is to give a detailed description of the TDCS transmitter and receiver systems and to highlight the fundamental differences relative to OFDM and MC-CDMA. The fundamental idea in TDCS is to synthesize a smart adaptive waveform to avoid interference at the transmitter instead of the more traditional mitigating of interference at the receiver. Unlike OFDM and MC-CDMA, TDCS has very little exposure in the current literature.

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A new algorithm is presented for Automatic Target Recognition (ATR) where the templates are obtained via Singular Value Decompositioiz (SVD) of High Range Resolution (HRR) profiles. SVD analysis of a large class of HRR data reveals that the Range-!3pace eigenvectors corresponding to the largest singular value accounts for more than 90% of target energy. Hence, it is proposed that the Range-space eigen-vectors be used i s templates €or classification, The effectiveness of data ncirmalization and Gaussianization of profile data for improved classification performance is also studied. With extensive simulation studies it is shown that the proposed Eigert-template based ATR approach provides consistent superior performance with recognition rate reaching 99.5% for the four class XPATCH database.

Several studies have revealed that spectrum congestion is primarily due to the inefficient use of spectrum versus unavailability. Cognitive Radio (CR) and Ultra Wide Band (UWB) technologies have been proposed as candidates to address this problem. Currently, a CR determines unused frequency bands and transmits overlay waveforms in these bands, while UWB transmits underlay waveforms that span the entire frequency band while coexisting with primary users. This suggests that most of the spectrum occupied by primary users is underused. This work proposes a general Soft Decision Cognitive Radio (SDCR) framework, based on a previous developed SpectrallyModulated, Spectrally Modulated (SMSE) framework, to combine benefits of overlay/underlay techniques while maximizing channel capacity. We also show that current CR and UWB implementations represent two extreme SDCR cases and that current overlay/underlay waveforms are two special cases of the general waveform platform.