We investigate the performance of priority-based access in a channel-hopping cognitive network, in particular the interaction between the number of packets each node is allowed to send in a single transmission cycle and the penalty coefficient that determines the amount of sensing to be done upon a successful transmission. Our results indicate that giving higher bandwidth allocation to low prio...

SUMMARY A novel peak-to-average power ratio (PAR) control algorithm for feedback-controlled multitone-hopping code-division multiple access (FC/MH-CDMA) signals is proposed. In FC/MH-CDMA, since each chip consists of plural tones, the energy consumption due to a large PAR is not negligible at the transmitter. The proposed PAR control algorithm iteratively constructs a time-frequency code that a...

Under perfect synchronisation conditions, watermarking schemes employing asymmetric spread-spectrum techniques are suitable for copy-protection of audio signals. This paper proposes to combine the use of a robust psychoacoustic projection for the extraction of a watermark feature vector along with non-linear detection functions optimised with side-information. The new proposed scheme benefits f...

In this paper, a DCT-based blind watermarking scheme based on spread spectrum communications is proposed. We perform block-based DCT on the host image; then using the DC coefficients of each block, we construct a low-resolution approximation image. We apply block-based DCT on this approximation image, then watermark is embedded by adding a pseudo random noise sequence into its high frequencies....

In this paper, a new method of pulse compression polyphase code synthesis based on the aperiodic autocorrelation function properties and the assumption of coherent processing in the radar receiver is presented. Properties of the proposed code, including spectrum, ambiguity function, precompression bandlimiting effects, and the noise/clutter influence are analyzed. The main features of the synth...

Among the many techniques available for information concealment, those based on spread spectrum modulations have proven to yield improved results when robustness against attack is at a premium. In this paper, we propose a new spread spectrum-based watermarking procedure that combines space and frequency marks to provide good robustness properties against both spatial (affine) and transform-base...

We study a totally asymmetric simple exclusion process (TASEP) with one defect site, hopping rate q < 1, near the system boundary. Regarding our system as a pair of uniform TASEP’s coupled through the defect, we study various methods to match a finite TASEP and an infinite one across a common boundary. Several approximation schemes are investigated. Utilizing the finite segment mean-field (FSMF...

One digital watermarking method, based on the spread spectrum technique, is described in this paper. This method uses the frequency hopping spread spectrum in order to determine positions for watermark embedding in an original image, while the direct spread spectrum technique is used to provide robustness to the watermark signal. To embed the watermark signal, the selected bits are used to carr...