Research And Implementation Of Channel Estimation And Equalization Technology In Scatter Communication

Tropospheric scatter communication is an over-the-horizon communication method.Because of its strong confidentiality and strong anti-interference characteristics,it occupies an important position in the field of military communications.Channel estimation and equalization technology is one of the keys to ensure the performance of the scattering communication system.This article mainly focuses on the channel estimation and equalization algorithm under the scattering channel,and completes the design of the scattering communication system and the implementation of the channel estimation and equalization on this basis.First,the transmission loss and fading characteristics of the scattering channel are analyzed.Aiming at the multipath effect and Doppler effect of the scattering channel,the tropospheric scattering channel model and the corresponding multi-tap channel model are determined to provide a theoretical basis for the optimization of the channel estimation and equalization algorithm and the design of the scattering communication system.Aiming at the channel estimation algorithm in the scattering communication system,this paper proposes an improved DFT-based channel estimation algorithm based on the analysis and research of traditional Least Squares estimation algorithm,Linear Minimum Mean Square Error estimation algorithm and DFT-based channel estimation algorithm.This algorithm obtains the effective channel and noise division threshold based on the estimated values of noise power and channel gain,and further improves the performance of the channel estimation algorithm by filtering out the noise.Aiming at the equalization algorithm in the scattering communication system,this paper analyzes and compares the commonly used linear equalization algorithms,including Zero Forcing equalization and Minimum Mean Square Error equalization,focusing on the timefrequency domain Hybrid Decision Feedback Equalization algorithm,and proposes a HDFE-MMSE-RISIC equalization algorithm.This algorithm uses time-domain feedback filtering to more accurately complete the symbol selection decision,improve the estimation accuracy of residual inter-symbol interference,and effectively improve the error performance of the equalization algorithm.Furthermore,this article extends it to the MIMO system,and the simulation results show that compared with the traditional equalization algorithm,the performance of the improved algorithm is better.Finally,the channel estimation and equalization module in the scatter communication system in this paper is implemented on FPGA,including key modules such as pilot separation module,channel estimation module,equalization module and STBC decoding module,and has passed system-level and board-level test verification.