Research On Measurement Method Of Wireless Channel Transmission Characteristics In Complicated Mountain Environment

In wireless communication network construction,especially military,disaster relief and other emergency communication site layout process,it is necessary(important)to carry out scientific research on channel measurement and estimation of complex mountain environment.Thus,to ensure effective and reliable communication under special channel conditions in application scenarios.It includes accurately measuring the large-scale and small-scale fading characteristics of wireless channels in complex mountainous environment.These works capable of providing data support for the optimal deployment of communication sites in mountainous environment,and providing effective guarantee for the rapid opening and reliable communication of emergency communication network.However,in the mountainous environment,the noise and interference of the emergency communication frequency are serious.The multipath delay is inhomogeneous and sparse.All of them bring great challenges to channel measurement.Facing these challenges,this dissertation aims at studying the measurement methods of wireless channel transmission characteristics under complex mountainous environmental conditions.The main work is summarized as follows:(1)Aiming at the traditional sliding correlation method problems that correlation peak overlap and inter-path interference exist in measuring the fading parameters of large and small scale channels,an improved sliding correlation method is proposed.This method can correct the amplitude error caused by "inter-path interference",so as to reduce the error of subsequent channel parameter extraction.(2)Aiming at the problem of serious noise interference in the emergency communication frequency band,channel denoising algorithm is studied and a wavelet denoising algorithm based on multi-objective particle swarm threshold optimization is proposed.Simulation experiments show that the algorithm has good denoising performance under the condition of small signal-to-noise ratio and it can effectively filter the noise interference of wireless channel.Thus,it reduce the root mean square error of useful signal.(3)Aiming at the problem of difficult estimation of multipath time delay distribution caused by wireless signal multipath overlap and extremely uneven time delay distribution of emergency communication frequency band in mountainous environment,the high resolution multipath time delay estimation algorithm is studied.A GSCC-WRELAX algorithm is proposed,which is based on the fusion of generalized secondary cross correlation(GSCC)algorithm and weighted Fourier transform and relaxation(WRELAX)algorithm.Simulation results show that GSCC-WRELAX algorithm still has good performance when estimating small multipath delay interval.In the experiment,all the above are jointed to measure wireless channel parameters in mountain environment.It verifies that the proposed method is effective in measuring the transmission characteristics of wireless channel in mountainous environment.Meanwhile,an Ablation Experiment of the measurement method is carried out,which quantifies the improvement in measurement precise of the proposed method.