Research On Channel Parameter Extraction Algorithm For 5G Application

On the one hand,in order to meet the requirements of future communication networks,the design and evaluation of various advanced wireless communication technologies requires a channel model that can capture the characteristics of the technologies presented on the corresponding channels.Some random channel models based on geometry have been widely accepted by the industry,but to adapt to specific application scenarios,channel parameters of various scales need to be input to them,and these parameters can only be obtained from a large number of actual channel measurement data.Commonly used multi-dimensional channel parameter extraction algorithms,such as space alternating subspace generalized expectation maximization(SAGE),are essentially multidimensional parameter iterative estimation methods based on likelihood functions.In order to describe the channel accurately,it is necessary to estimate the parameters of the large quantum path,which is highly complex and easy to estimate the false path.On the other hand,the current base station system deploying 5G new radio(NR)technology adopts beamforming technology to improve system capacity,so the acquisition of uplink Angle domain parameters is particularly important.The uplink of the NR system uses the channel sounding reference signal(SRS),but the station deployment at present mainly uses it to obtain channel frequency response(CFR).Only rough Angle information can be obtained from CFR using conventional direction of arrival(DOA)localization techniques.Therefore,the channel parameter extraction algorithm with low complexity,high efficiency and suitable for NR system has direct and indirect research significance in the field of channel detection and base station beam resource optimization.Under the background of 5G large-bandwidth multi-antenna technology,aiming at the application of channel measurement in high-speed mobile scenarios and NR uplink Angle information extraction,this paper proposes a low complexity and efficient channel multidimensional parameter extraction framework based on the characteristics of channel spacetime separation,which can extract delay,azimuth,elevation,Doppler shift and complex amplitude parameters of large quantum paths in channels.In this paper,the channel neutron path is separated from the spatial domain and the time domain,and different algorithm modules are used to calculate different parameters of the sub-path,instead of iteratively searching to maximize the maximum likelihood function of all sub-path parameters.Because it utilizes the characteristics of channels and is designed according to them,it not only reduces the complexity compared with SAGE,but also avoids the problem of false paths.In order to describe the principle and content of the proposed method,the extraction principle of parameters in different domains is introduced.It also introduces SAGE principle,DOA algorithm principle,spatial smoothing principle,and the problems of spatial fading,power leakage of channel impulse response(CIR),ill-conditioned matrix and phase ambiguity in practical system application,so as to illustrate the idea of putting forward the algorithm and the process of continuous improvement.Finally,the algorithm is not only suitable for channel measurement in high-speed mobile scenes,but also can be used to extract fine and effective Angle information from CFR of NR base station.In the aspect of algorithm simulation,in order to illustrate the correctness of the algorithm,we firstly introduce the principle of parameter estimation in different domains and carry out corresponding simulation at the same time,verify the function of each parameter extraction module and get its performance.Then,the proposed method is compared with SAGE on the artificial multipath channel platform.The results show that the proposed method not only has better performance in high-speed mobile scenarios,but also has better performance in terms of time and extraction effect for sub-path parameters than SAGE.To demonstrate the universal applicability of the proposed algorithm,the proposed algorithm is also used to extract channel parameters in CIR generated by quasi deterministic radio channel generator(Qua DRi Ga),and get parameters in line of sight(LOS)and non-line of sight(NLOS)scenarios.The results show that the CIR reconstructed with the extracted parameters is basically consistent with that generated by Qua DRi Ga.In practical NR system application,in order to verify the accuracy of the method proposed in this paper in extracting Angle information from base station data.We not only compared it with the forward-backward spatial smoothing multiple signal classification(FBSS-MUSIC)algorithm in terms of angular power spectrum.Moreover,the beam receiving power of base station is used to verify the parameter extraction of the proposed algorithm.The results show that in the application of NR system,compared with FBSS-MUSIC algorithm,the proposed method can extract more effective spatial Angle information of LOS scene.