Browsing by Author "Spooner, Chad M."

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    Eigenspace Approach to Specific Emitter Identification of Orthogonal Frequency Division Multiplexing Signals
    Sahmel, Peter H. (Virginia Tech, 2011-11-16)
    Specific emitter identification is a technology used to uniquely identify a class of wireless devices, and in some cases a single device. Minute differences in the implementation of a wireless communication standard from one device manufacturer to another make it possi- ble to extract a wireless "fingerprint" from the transmitted signal. These differences may stem from imperfect radio frequency (RF) components such as filters and power amplifiers. However, the problem of identifying a wireless device through analysis of these key signal characteristics presents several difficulties from an algorithmic perspective. Given that the differences in these features can be extremely subtle, in general a high signal to noise ratio (SNR) is necessary for a sufficient probability of correct detection. If a sufficiently high SNR is not guaranteed, then some from of identification algorithm which operates well in low SNR conditions must be used. Cyclostationary analysis offers a method of specific emitter iden- tification through analysis of second order spectral correlation features which can perform well at relatively low SNRs. The eigenvector/eigenvalue decomposition (EVD) is capable of separating principal components from uncorrelated gaussian noise. This work proposes a technique of specific emitter identification which utilizes the principal components of the EVD of the spectral correlation function which has been arranged into a square matrix. An analysis of this EVD-based SEI technique is presented herein, and some limitations are identified. Analysis is constrained to orthogonal frequency division multiplexing (OFDM) using the IEEE 802.16 specification (used for WiMAX) as a guideline for a variety of pilot arrangements.
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    Paramorphic multicarrier communications for interference mitigation
    Carrick, Matt; Reed, Jeffrey H.; Spooner, Chad M. (2018-01-05)
    This paper presents a novel method for enabling communication in cyclostationary interference limited environments by adaptively inserting and exploiting spectral redundancy in an orthogonal frequency division multiplexing (OFDM) signal. The redundancy is formed through repeating data symbols across OFDM symbols in both time and frequency. A novel frequency shift (FRESH) filter is applied to exploit the time-varying cyclostationary properties, enabling the communication while under interference. The ability to design an interference mitigating property into the communication signal creates a new degree of freedom when optimizing and adapting a waveform’s parameters. Simulation results demonstrate the performance gains in both signal to interference and noise ratio (SINR) and bit error rate (BER) as compared to traditional time-invariant optimal filtering techniques and error correcting codes (ECC).