Broadband Shortwave Channel Characteristics And Modeling Studies

The research of wide band high frequency (WBHF) channel is the base ofdevelop wide band large capability HF communication systems, but traditionalresearch about HF channels is limited to narrow band signal transport so they can'tsuit wide band high speed HF data transport. Since early 1980' scientists have begunto research WBHF channels conditions especially skywave transport methods to builtchannels models, but to this day it hasn't give a universal accept channel model, sowe can see the complexities of WBHF channel characteristic. In this study, we studythe WBHF channels physical characteristic , introduce and evaluate WBHF modelingmethods, finally realize a WBHF channel model which is efficient computersimulation model for WBHF channel. First, the chapters 1 is a forward of this dissertation, we introduce basic HFcommunication characteristic and the development history and today's state about HFchannels research especially about WBHF channels research. At the end of thischapter we present the purpose and contribution of this dissertation. The 2nd chapter of this dissertation describes HF radio wave propagationproperties and fundamental channels properties, and it's one of the emphases of thisdissertation. Ionosphere delaminating has been described first to explain therelationship about radio wave reflect height and time of day. Like radio wavepropagate through other medium, HF radio wave have some fundamental physicalphenomenon as attenuation, reflection, refraction, diffraction, fading, scattering,dispersion, Doppler shift and spread, group path delay etc, they have important tounderstand HF channels. Polarization mode separation is an important phenomenon atsky wave propagation; to explain that the Appleton-Hartree equation is described.Multipath and fading phenomena as an emphasis are described in this chapter toprepare modeling channels. Finally, propagation loss is described to theoretic sustainlink budget at system design. The 3rd chapter of this dissertation describe channel modeling concept, modeling 第 iii 页电子科技大学 硕士学位论文ideas and give the methods how to validate the model will simulated. Wirelesschannels dynamic characteristic about scattering function and fading Stat.characteristic are discussed as emphases to validate the simulated model which willdiscussed in chapter 5 and 6. The 4th chapter of this dissertation describes the classic watterson narrow bandHF (NBHF) channel model and other WBHF channels which are derived fromwatterson model. After analyze their characteristics, we choose the ITS model tosimulate by computer. The 5th& 6th chapters are other emphases of this dissertation which describe theITS WBHF channel model mathematic structure and modeling structure. We discusshow to realize the computer model properly such as harmonious splice method torealize rayleign fading, and give the simulation data and result. The last chapter is the summing-up of this dissertation and proposes thefollowing research direction.