Study On The Adaptability Of OFDM/OQAM Communication System Against Fast Fading Channel

In wireless communication system,high-speed information transmission is required by people,so in the 4G,OFDM/CP becomes the modulation mode 4G in down-link with its excellent anti multi-path ability.In a fast fading environment,the information is impacted by Doppler frequency,however,the OFDM/CP system is easily sensitive to the Doppler frequency shift,the high-speed transmission of OFDM/CP system is limited in fast fading channel.In order to enhance the robustness of the OFDM system in the Doppler frequency shift,in this paper,the OFDM/OQAM system will present a new way to improve the situation owing to the pulse shaping function which has the characteristics of good time-frequency aggregation,therefore the system for the Doppler frequency shift of the resistance ability enhancement.In the OFDM/OQAM with the more robustness of more Doppler frequency than OFDM/CP system,however the basic function of OFDM/OQAM is only to meet the real domain orthogonal,the system is very sensitive to imaginary coefficient in the channel impulse response,which will cause the system to produce the imaginary part of the interference at the receiving end,in order to eliminate the interference from the imaginary part,in this paper pilot design,channel estimation,channel equalization will be used to decrease imaginary part of the interference,reduce the influence of the imaginary part of the interference to OFDM/OQAM system.The concrete research content of this paper are arranged as follows:First of all,the digital base-band model of the OFDM/OQAM is established in the theoretical study,in which the full research is put in the EGF group,that is to say,the discrete IOTA function which is the pulse shaping function in the paper is obtained from EGF continuous functions.Secondly,the modeling of the broadband channel is established,which mainly includes PLC,COST207-TU,express A channel model.Basic channel model is Ruili channel and the Doppler frequency shift of the model is the classical Jake type.Subsequently,in pilot design of OFDM/OQAM system,pilot based on interference cancellation is put forward and the analysis on the receiving end of each pilot status of virtualnumerical value between distribution is presented.Again,in the channel estimation of OFDM/OQAM system,the methods of channel estimation based on the interference-used is put forward.Finally,in the channel equalization of OFDM/OQAM system under the absence of channel coding case,the simulation of OFDM/OQAM system will be carried out respectively in slow fading and fast fading channel to prove the method proposed in this paper,obviously,shortcomings of the method will be pointed out.