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We investigate the performance of frequency division multiplexed (FDM) signals, where multiple orthogonal Hermite-Gaussian carriers are used to increase the bandwidth efficiency. Multiple Hermite-Gaussian functions are modulated by a data set as a multicarrier modulation scheme in a single time-frequency region constituting toroidal waveform in a rectangular OFDMA system. The proposed work outperforms in the sense of bandwidth efficiency compared to the transmission scheme where only single Gaussian pulses are used as the transmission base. We investigate theoretical and simulation results of the proposed methods.

Abstract-An interference excision algorithm in direct-sequence spread spectrum (DS-SS) communication systems is introduced. The proposed excision algorithm is developed for linear frequency modulated (LFM) signals that have broadband frequency characteristics. It is based on the time-frequency analysis of received signals employing short-time Fourier transformation (STFT). To analyze the interference, STFT of the received signal block is evaluated and thresholded. The interference detection is followed by an inverse-STFT computation to estimate the high-power jamming signal. The estimated jammer is then mitigated before demodulation. Simulations present adequate interference estimation results with mean estimation errors less than 0.01%. Various scenarios with different jammer-to-signal ratios (JSRs) and signal-to-noise ratios (SNRs) vs. bit error rates (BERs) are presented for single and multi-component LFM signals. Interference excision algorithms improve the system performance more than an order of magnitude.

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Accelerated investments on wind power projects because of the great demand for renewable energy are increasing the concerns about deteriorating effects of wind turbines on the performance of civil and military radar, navigation and communications systems. In this study, the authors introduce a preliminary set of analysis for assessing the performance of electronic systems such as radar, communications and navigation systems and the degrading/deteriorating effects of wind turbines. The analysis quantifies the performance degradation in the electronic systems. The proposed study can be used as a tool by decision makers in the planning and designing phases of both electronic systems and wind turbines to reduce the adverse effects of the wind farms on the mentioned systems.