Research On OFDM/OQAM Channel Estimation Techniques

Orthogonal Frequency Division Multiplexing / Offset Quadrature Amplitude Modulation(Orthogonal frequency division multiplexing /offset quadrature amplitude modulation,OFDM/ OQAM),which belongs to the generalized rate of frequency division multiplexing(generalized frequency division multiplexing,GFDM).OFDM / OQAM system is stronger than conventional anti-OFDM system in terms of the ISI and the ICI.It is widely used because of it's no cyclic prefix and and low-band radiation.But the advantages of OFDM / OQAM system where are orthogonal to relax the conditions and further introduced some time having excellent focus characteristic frequency shaping filter as the price,so the traditional channel estimation method for OFDM systems no longer fit with OFDM / OQAM system.So aiming at this problem,this paper proposes a combination of wavelet transform and weighted OFDM/OQAM subcarrier channel estimation algorithm for each of the following problems are studied.(1)This paper studies the OFDM/OQAM channel estimation algorithm based on the structure of IAM pilot principle,compares the performance of channel estimation algorithm under different pilot structure,and through the experimental simulation found IAM3 pilot structure is under the precondition of the IAM pilot energy unchanged the optimal pilot structure.The experimental results show that based on the pilot IAM3 structure under the condition of the same channel than based on IAM1,IAM2 pilot structure has lower bit error rate.(2)For OFDM/OQAM channel estimation with noise problem.This article through the analysis of the frequency domain expression of channel frequency response,discovery channel noise in the frequency domain exists in the form of additive noise,can through the frequency domain to improve the channel estimation noise is reduced.Because the wavelet transform in frequency domain has good multi-resolution analysis more features,this paper,wavelet de-noising is applied to channel estimation to improve the performance of channel estimation.(3)For child intercarrier interference will affect the channel estimation performance problems.Estimate the weighted algorithm,this paper studies the sub-carrier found sub-carrier weighted treatment can effectively increase the channel gain.The applications of subcarrier weighted to effectively improve the channel in the channel estimation performance.(4)The optimal pilot structure,finally,the paper combines the wavelet denoising andsubcarrier weighted algorithm,and the simulation experiment,the experimental results show that the algorithm improved the performance of channel estimation,effectively reduce the channel bit error rate.