Research On Broadband Wireless Transmission Technology Based On High-Speed Mobile Scenarios

From the development of future mobile communication,systems will face more application scenarios and more complex transmission environments.Especially,highspeed mobile scenarios have become important application scenarios for future mobile communication.In a high-speed mobile environment,the mobile station will be in a highspeed motion state,resulting in the wireless signal being affected by the Doppler effect and the reliability of signal detection being reduced.Orthogonal frequency division multiplexing(OFDM)technology is widely used.Although it can resist inter carrier interference(ICI)and inter symbol interference(ISI),it is very sensitive to Doppler effect in high dynamic environments.Therefore,in order to adapt to high-speed scenarios,it is imperative to improve the transmission capacity of OFDM.In response to this issue,this thesis optimizes the design of OFDM systems based on high-speed mobile transmission environments.Firstly,channel estimation techniques were studied.Due to the rapid channel changes in high-speed mobile environments,in order to ensure reception performance,it is necessary to increase the pilot density for channel estimation,resulting in a decrease in spectral efficiency.Firstly,the channel response estimation algorithms using pilots are analyzed and compared,and the pilot pattern design in compressed sensing(CS)technology is expanded.Furthermore,based on existing channel estimation schemes,a data assisted channel estimation algorithm is proposed,which can improve the detection performance of OFDM systems with a certain pilot density.Secondly,the ICI self-cancellation technology was studied.Due to the difficulty of directly eliminating ICI caused by Doppler spread in the receiver,this thesis proposes to eliminate ICI through coding design at the transmitter.Firstly,several classic coding schemes were analyzed through a combination of theory and simulation,and a brief introduction was given to the scheme of using ICI self-cancellation for channel estimation.Given that existing schemes improve performance by sacrificing spectral efficiency,this thesis proposes an efficient ICI self-cancellation method that reduces the impact of ICI in OFDM systems without reducing transmission efficiency.Thirdly,the orthogonal time frequency space(OTFS)technology in high-speed mobile channels was studied.On the one hand,the differences between the OTFS joint channel model and the actual model were revealed,and effective signal detection methods for the actual channel were pointed out.On the other hand,a low complexity detection algorithm based on N-Cyclic Prefixes(N-CP)was proposed,and the system performance of Index Modulation(IM)OFDM and OTFS was measured based on the proposed new detection algorithm.In summary,this thesis conducts research on broadband wireless communication OFDM technology in high mobility scenarios.Starting from receiver detection and transmitter design,a series of improvement schemes are proposed to improve system performance,which has good reference significance for the design of multi-carrier systems in high-speed mobility scenarios.