Research On TOA Estimation Technology Based On 5G Uplink Sounding Reference Signal

With the continuous evolution of the protocols of the 5th Generation mobile Networks(5G),the application scope of communication networks is gradually expanding.The demand for indoor positioning is increasingly urgent in all walks of life.Due to noise,multipath effect,time synchronization and other factors,5G base station is still unable to provide reliable location services.Based on the 5G uplink sounding reference signal(SRS),this paper studies the key technologies of 5G system to achieve high precision positioning in indoor environment,time of arrival(TOA)estimation technique.The current TOA estimation algorithms based on correlation all have the shortcoming that the system bandwidth limits the resolution.A high resolution TOA estimation algorithm based on 5G SRS is proposed by this paper,which achieves high resolution estimation through secondary correlation.Firstly,the Least Mean Square(LMS)adaptive filtering method is used to preprocess the received signal,and the integer part of TOA estimation is obtained.Before the secondary correlation,cubic spline interpolation(Spline)was used to interpolate the received signal.Then,Generialized cross-correlation(GCC)estimation method based on phase transformation(PHAT)weighting function is used for secondary correlation estimation,and the fractional part of TOA estimation is obtained.Finally,the dynamic threshold set by LMS filtering results is used to obtain the final TOA estimation.The results of simulation show that the positioning accuracy of the proposed algorithm is 0.56 m and 0.96 m respectively in the additive white Gaussian noise channel and the Rayleigh fading channel,reaching submeter accuracy.For indoor complex multipath environment,MUSIC estimation algorithm based on subspace is improved in this paper.In the Saleh-Valenzuela(S-V)channel,the channel estimation algorithm combining Least Square(LS)channel estimation method and Discrete Fourier Transform(DFT)channel estimation method is used to solve the channel impulse response.Then,the spatial smoothing algorithm is used to solve the covariance matrix of the observed signal,and the pseudospectrum is carried out.Finally,the TOA estimation is obtained by detecting the peak value of the pseudospectrum.Simulation results show that the root mean square error of the proposed algorithm is only 1/3of that of the traditional method in indoor multipath environment,which improves the reliability of the estimation results.