Enhancing the Power Spectral Density of PPM TH-IR UWB Signals Using Sub-Slots Technique

摘要

The suppression of the spectral line is an issue of large interest in the design of compliant Time Hopping Impulse Radio (TH-IR) Ultra-Wide Band (UWB) systems. This issue has been previously addressed by randomizing the position of each pulse to make the period as large as possible. Our analysis suggests that randomizing the position of each pulse influences the overall shape of a signal's Power Spectral Density (PSD) in a way useful for spectral line suppression and diminishing the PSD maximum peak power. The method and system for generating a Dynamic Location Pulse Position Modulated (DLPPM) signal for transmission across an UWB communications channel are presented. An analytical derivation of the PSD of a DLPPM signal TH-IR UWB is introduced. Our proposal can be applied without affecting the users of other concurrent applications. The theoretical model for DPLM TH-IR is compared with the PSD for conventional Pulse Position Modulation (PPM) TH-IR. The results show that Fast Fourier Transform (FFT) based spectral estimation methods significantly overestimate the continuous part of the PSD for small and medium signal lengths, which have implications in assessing interference margins by means of simulation. Finally, the proposed system for DPLM TH-IR has been built inside Simulink/MATLAB to test its results via conventional PPM TH-IR system.