Research On The Influence Of Deep Space Channel Fading Characteristics On Space Communication Protocols

Deep space exploration is a s pace activity expanded into the broader solar space,which is based on the major achievements in the fields of artificial satellites,manned spaceflights,and lunar exploration.Distributed network detection is one of the important trends in deep space exploration.Because of the long communication distance,severe signal energy attenuation,low signal-to-noise ratio,and complex link environment,large-scale fading,long time delay and intermittent interrupt are the existing characteristics in the deep space physical channels.The application of existing space communication protocols in deep space channels have problems such as low data throughput and serious link congestion,because they are mostly originated from the derivation or modification of terrestrial communication network protocols.Therefore,in the distributed network exploration task,the physical channel characteristics must be first researched as the dependence of the space communication protocols.This paper researched the influence of channels fading characteristics on the space communication protocol under deep space network communication scenarios.The purpose was aimed to start from the physical environment of signal transmission,explore the deployment method of deep-space networking communication protocols,and solve the key technologies such as low throughput and link congestion applied in deep space communication scenarios,provide reference for the planning and design of deep space network protocols.The research contents were mainly included:(1)Based on deep-space communication scenarios of electromagnetic wave signal transmission,the inherent fading characteristics,intermittent interruption characteristics,long time delay characteristics of deep-space channels and their impact on s ignal transmission were analyzed.The key point was the simulation and calculation for the amplitude fading,spectrum expansion and phase flicker caused by the sun scintillation,the atmosphere fading,and large-scale free-space loss.(2)In order to resist the impact of the scintillation of the sun on the signal transmission,a parameter design method suitable for the interplanetary communication link was proposed.This method can be used to calculate the amplitude statistical characteristics and time spectrum characteristics accoding to the effect of the plasma impact on the radio waves transmission.This method also related with the geometric relationship between the communication link and the sun.The calculation results can be used as the constraints in the frequency selection of the communication link,the bandwidth design of the transmission signal,and the modulation method selection,and the phase loop bandwidth design.(3)The model of existing space protocols and the realization function of each part were present,and the development trend of TCP/IP protocol,CCSDS protocol,DTN protocol were analyzed,especially their problems applied in deep space network communication scenario.(4)The infuence of the deep-space channel characteristics on the protocol was studied.The effect of the bit error rate on the protocol throughput,the influence of the long time delay on t he protocol handshake mechanism,and the impact of the interruption on t he protocol retransmission mechanism were simulated and analyzed.(5)Taking the Mars communication scenario as an example,a Earth-Mars networking protocol architecture was constructed,and a v irtual simulation platform based on STK-ION-CORE was established.The bit error rate,time delay,and interruption were applied to the TCP,LTP,and SCPS-TP protocols.Then,a segmental deployment method of communication protocol was proposed,which was called TLU.In this method,the whole link was split into three segment: the Earth base station & the relay satellite,the relay satellite & Mars orbiter,Mars orbiter & Mars base station.The communication performance of the three segment protocols were simulated and analyzed,the result showed this method can fit this network scenario.The innovations of this topic include:1)Aiming at the influence of the channel fading characteristics on the space communication protocols in deep space communication link,a segmentation method for protocol deployment was proposed.This method focused on the physical layer to solve the reliable linking problem in the deployment of the space networking protocol,and can be used as the design reference of upper layers.2)Based on the analysisness of infuence of amplitude fading,spectrum expansion,and phase flicker caused by the sun scintillation in the radio waves transmission,taked the similation results of the influence on the S,X,and Ka frequency bands as senarios,a parameter design method of interplanetrary communication link under the influence of the solar scintillation was proposed.This method can be used as the basis for parameters design of deep space communication links.3)Aiming at the coexistence of multiple heterogeneous protocols in space networking,a method for blind identification of space link protocols was proposed.This protocol indentification method would be used to realize the recognition and recognition of non-cooperative target protocol features,and provided a reference for the integration of spatial networking heterogeneous protocols.Finally,the future research direction of the subject was summarized and forecasted.