Research On Channel Estimation Algorithm For OFDM Systems Based On Wavelet Denoising

Since the LTE proposed by 3GPP organization based on UMTS as a standard of next generation wireless communication system,the OFDM and MIMO has become the two key technologies of the LTE system because its excellent performance.Channel estimation,as a key technology to determine the performance of OFDM system,has been one of the research hotspots in the field of mobile communication.In this paper,our research is based on the channel estimation algorithms based on pilot.Firstly,due to multipath fading of wireless channel and the influence of the Doppler frequency shift,this paper used the MATLAB simulation results to analyze its influence on the performance of wireless broadband communication systems;And then combined with OFDM orthogonal frequency division multiplexing technology,using ODFM high spectrum efficiency,anti-interference ability,transmission speed and other characteristics,can effectively resist multipath fading,raise the utilization rate of spectrum,Finally,the paper focuses on the channel estimation technique in OFDM system,in accordance with technical data as defined by the 3GPP standard,combined with the continuous development of OFDM technology and communication technology,the advantages and disadvantages of the traditional channel estimation algorithm is analyzed in detail,and then make their own improved algorithm idea:(1)The channel estimation algorithm based on DFT can eliminate the noise outside of the cyclic prefix length,but it did not make a deal for the noise within the cyclic prefix length.In view of the above problems,some improved DFT based channel estimation algorithm has been proposed,the so-called improvement is the use of time to eliminate the noise threshold within the cyclic prefix.Based on the analysis of various modifications DFT algorithm,On the basis of analyzing all kinds of improved DFT algorithm,this paper proposes a new channel estimation algorithm for ODFM system based on wavelet analysis and improved DFT.(2)The estimation performance of the DFT based channel estimation algorithm is better than the LS channel estimation algorithm,but because of the existence of the virtual sub carrier,the energy spread and the spectrum leakage can be caused.In view of this problem,this problem can be solved by using the symmetric extended DFT transform;This paper proposes a new channel estimation algorithm for ODFM system based on wavelet analysis and symmetric extended DFT.After the theoretical analysis of the improved algorithm,and design the algorithm process,obtains the corresponding code according to the process of the algorithm,using MATLAB 2012 b of corresponding code simulation.Simulation results shows that the improved algorithm in the same environment,the bit error rate(BER)and the mean squared error(MSE)have decreased,the performance of the whole system has also been improved.