This paper introduces the reasons and classification of wireless space fading, statistical characteristics of different types of channels. Through the analysis of reentry channel characteristics, we select the two pathes frequency selective slow fading channels.The spectral density function of Doppler power about two scattering path is derived.Channel model is established by rician method.Then determine the channel model parameters and simulate the wireless fading channel model with Matlab／Simulink software Keywords:Reentry process,wireless fading channel,rician method
1．the introductionSince 1999,when Shenzhou spacecraft was successfully launched, China has opened the prelude of deep space exploration. with the development of the aviation industry, When spacecraft return, which passed four stages: aberrancy, interim ,reentry and landing . When entering the reentry vehicle, the communication between Aircraft and ground control station is special. Firstly, The electromagnetic wave spread in wireless channel, which occur Reflection, Scattering and Diffraction with the ground, mountains, trees and other obstacles reflection. The ground stations received a superposition of multiple paths, which called multipath effect. Because the distance between the aircraft and station so far , make the time delay between different path is bigger. Secondly, the capsule reentry return, it has the characteristics of high speed and dynamic change, so there is a high dynamic Doppler effect. Thus it can be seen that study the anti fading channel is the key to the stable and reliable landing of spacecraft.
2．wireless spatial channel characteristicsWhen the spacecraft into reentry period, it communicate with the ground control station that is wireless channel. Due to the influence of multipath effect, different path components that amplitude, phase and arrival time and the incidence angle are different. They are make the received composite signal in amplitude and phase have a serious distortion, which occurred in the multipath fading.
2．1 wireless Spatial Channel CharacteristicsMultipath effect can generate the time dispersion effect and frequency selective fading, Doppler effect will generate the frequency dispersion effect and the time
