Optical Generation And Transmission Of Ultra Wideband Signals Based On Optical Pulse Shaping

With the advantages of ultra wide frequency band, effectively resist of multipath fading, low emission power, low energy consumption and reutilization of the existing spectrum resources, ultra wideband (UWB) has been one of the research hotspots of wireless access technologies. Since the establishment of standards of24GHz UWB system using for road safety and vehicle communication by ETSI, UWB signals with high speed and high frequency have got widely attention. On the other hand, according to the regulation of FCC and ETSI, UWB signals have an ultra low PSD distributed in several GHz frequency range, which enables them appropriate for wireless communication without affecting the existed communication systems on the one hand, whereas susceptible to be annihilated by channel noise on the other hand. Thus the generation of IR-UWB signals with maximum fill of FCC MASK is vital to the performance improvement of IR-UWB communication system.Based on the generation theory of UWB signals, electrical method and optical method are summarized. Through the comprehensive comparison, Optical pulse shaping (OPS) is chosen as the best way to generate the arbitrary UWB waveforms. The UWB generation system is based on OPS, and theoretical analysis and deduction of formulas are given. Simulated annealing algorithm is used as the optimization method and the spectrum efficiency (SE) is utilized as the optimization condition. The UWB signals with optimal SE are generated under the fixed system structure. The relationships of SE and energy efficiency (EE) are revealed. Then, the system structure optimization scheme using optical splitters with controlled splitting ratio is proposed. The simulation results show that the EE has been promoted substantially. Moreover, the relationship between the spectrum efficiency and the length of pulse trains and the robustness of the optical pulse shaper are analyzed. The results show the robustness of the optical pulse amplitude is quiet well, but the pulse delay should be controlled precisely.Finally, WDM and PDM are used for UWB signals optical transmission. The impact of optical dispersion is researched. Based on the simulation results, the compensation for dispersion and optimization of UWB generation and transmission are synthetically considered. The designed UWB signals are received at the receiving end and the overall system has good performance...