Research On Channel Estimation Technology For OFDM System And Exploration Of The LS Algorithm Implementation

The development of wireless communication technology has brought tremendous changes to daily life,not only changed people's communication methods,lifestyles,and working methods,but also greatly improved the quality of human life.In wireless communication technology,OFDM(Orthogonal Frequency Division Multiplexing)has attracted widespread attention due to its strong anti-symbol interference capability,high transmission efficiency,and high spectrum utilization rate.However,the wireless channel is very complicated.When the OFDM signal is transmitted in the wireless system,the amplitude will be attenuated and the spectrum will be shifted,which seriously affects the quality of the communication system.In order to ensure the reliable transmission of data,it is necessary to perform channel estimation at the receiving section.Channel estimation technology is one of the key technologies of OFDM system.This paper focuses on the performance of channel estimation based on the pilot pattern of 5G resource blocks,and proposes a piecewise interpolation algorithm based on the pilot pattern of this experiment,which is easy to implement in hardware.The following work has been carried out in this paper :(1)Introduce the OFDM system,the characteristics of wireless channel fading,and the types of channel estimation.The performance of different pilot patterns(block pilot,comb pilot,discrete pilot)in low and high-speed scenarios was analyzed;Based on the 3GPP TS 38.211 protocol,the system parameters and pilot patterns of this experiment were determined.(2)Build an OFDM system by Matlab.Including channel coding and decoding process,modulation and demodulation process,spreading spectrum non-spreading process,generating baseband signal process,channel estimation process,complete the entire link simulation.(3)In order to integrate with modern communication technology better,the experimental parameters and pilot patterns of this experiment are determined based on the 3GPP TS 38.211 protocol;The 3GPP TS 38.211 protocol describes the physicals channel and signal of 5G New radio(5G NR)channel,the pilot pattern is also based on the 5G resource block pilot pattern;On the built platform,complete the simulations of channel estimation algorithms,including: Least Square(LS)algorithm,Minimum Mean Square Error(MMSE)algorithm,Singular Value Decomposition(SVD)algorithm;And conduct the simulations of interpolation algorithms,including: constant value interpolation,linear interpolation,cubic interpolation;The system performance based on different algorithms is analyzed and compared.Based on the pilot pattern and pilot interval of this experiment,a piecewise interpolation method is proposed,and the interpolation coefficients can be adjusted accordingly,which is hopeful to achieve good performance and is easy to implement in hardware.(4)Since LS algorithm is the basis of the channel estimation algorithm,and has low complexity,simple structure,stable performance,and easy implementation,the LS channel estimation algorithm is implemented in a field-programmable gate array FPGA(Field-Programmable Gate Array).Each channel estimation module is described and analyzed.The use of piecewise interpolation algorithm behaves feasible and saves hardware resources.By comparing the FPGA simulation results with Matlab results,the bit error rate results are almost consistent,verifying the correctness of the LS algorithm simulation results on FPGA.