Research And Simulations Based On The ITS HF Channel Model

The HF communication systems propagate the information depending on the HFradiowaves reflected and scattered by thr ionoshphere.Because the characteristics of ionosperealways were affected by the changes of enviroment which made the radiowaves propagation withtime selective,frequncy selective and spatial selective fadings,finally,it will reduce thecommuniaction quality.the propagation performance and bandwidths of HF communicationsystem is inferior to the advanced sateliting,cell network and optical communications,howerver,because the propagation medium of HF communication is hardly to be destroyed by which theHF communication is irrepleced by other ones.The HF channel model is the theoretic and structural foundations to establish a HF channelmodel simulator.the experiments of HF communication will cost huge because of complicatedHF channel characteristic.It is most important to established a HF channel model which cansimulate the progress of HF radiowavs crossing the ionosphere.A reasonable HF channel model must should reflect the propagation characteristics of HFchannels totally.Firstly,the theise presents the propagation characteristics of HF channels and thedevelopment course of HF channel models,then selecting the classic Watterson HF channelmodel and ITS wideband channel to analyse and research.Finnaly according the results ofsimulation we proved that the Watterson channel model can replaced the ionospheric channel inlaboratory.Because of the limits of narrowband HF communication,the researchs on WidebandHF channel model becomes the tendency of reseaching on HF channel model.Finally,based onthe ITS model,we compared the simulation results of the sattering function with the NRL’slong-term test datas.Then concluding the ITS channel model can fit the Wideband channelsaccording the parameters which computed by the test datas.