Wireless Channel Measurement And Modeling Techniques In Tactical Ad Hoc Networks

Tactical mobile ad hoc network(TacMAN)is an important type of wireless mobile communication network in the field of military communication.It has the characteristics of strong flexibility,excellent reliability and high portability.In addition to military combat scenarios,it is also widely used in Public safety and emergency communications,such as field activities,rescue and disaster relief,etc.However,the characteristics of TacMAN are different from those of civilian communication,such as communication in the military frequency band and limited antenna height,which make it have completely different channel characteristics from civilian communication.The existing civilian cellular network channel models cannot be directly applied to TacMAN scenarios.In this paper,the TacMAN scenario is simulated to carry out field channel measurement,and a statistical channel model is established.The specific research work is as follows:(1)By summarizing the principles of commonly used channel detection methods and comparing the advantages and disadvantages of each,a broadband channel sounding system based on the time-domain spread spectrum sliding correlation method is built.After formulating the measurement plan with the actual measurement requirements,the channel measurement activities with three typical TacMAN scenarios of urban area,hilly area and air-ground communications were carried out in the urban and surrounding areas that can reflect the typical natural geographic conditions and population distribution in China,and the measurement data were pre-processed.(2)The statistical modeling methods applicable to TacMAN scenarios are summarized and improved.According to the significant difference between the altitudes of the transmitter and the receiver in air-ground communication scenarios,an elevation-angle-corrected large-scale fading path loss model is innovatively proposed to reflect the influence of the line-of-sight path elevation angle on the channel path loss.Combining with the characteristics of the alternating birth and death of multipath components existing in the measured data,a multipath identification and tracking algorithm is innovatively proposed,and an improved TDL model based on Markov chain is used to model the non-stationary process of the measured data.Based on the akaike information criterion(AIC),a statistical model of small-scale fading envelope distribution,Rice K-factor and delay spread is presented to analyze the small-scale fading characteristics and time dispersion of the channel.(3)Differential wireless channel models are established for three typical TacMAN scenarios,including large-scale fading model,multipath birth-and-death model and small-scale multipath channel model,and channel characteristics such as path loss,shadow fading,multipath existence probability,amplitude envelope distribution,Ricean K factor and delay spread were extracted.Combined with the characteristics of the measured environment,the influence of topography,obstacle distribution,receiver moving state and other characteristics on the statistical characteristics of the channel are studied,and the non-stationary phenomenon,fading process and time dispersion of the measured channel are further analyzed.The simulation results show that the model established in this paper considering the non-stationary characteristics of the channel can describe the channel characteristics in TacMAN scenario well,and provide reference for improving the performance of communication systems in the related military communication scenarios.