The OFDM System Based On Pilot Channel Estimation Method Of Research

In the future in the field of wireless communication, how to provide high speed, high quality and diversification of data service is one of the hot spot of research.Orthogonal frequency division multiplexing (OFDM) technology with its high data transfer rate, high spectrum efficiency and effective against frequency selective fading channel and other technical advantages received widespread attention.Channel estimation is one of the key technologies of OFDM system.One of its important role is that it has made it possible correlation demodulation, improves the performance of the system, the improvement of3dB.At the same time, the technology of adaptive channel estimation must be conducted, according to the change of the channel can change the way of modulation and coding rate and sending power of parameters, in order to maximize the send information, improve the system capacity.Therefore, the channel estimation is directly related to the merits of the system performance, its importance is obvious.In this paper, research of channel estimation based on OFDM system.First introduces the characteristics of the wireless communication, the conventional channel model and the basic principle of OFDM system and relevant technical indexes and the advantages and disadvantages of OFDM system.Channel estimation is one of the key technologies of OFDM system.Based on pilot channel estimation is known in the sender send signals, by selecting the appropriate algorithm, for processing of received signal channel frequency response.This paper mainly studied the Least Square, Minimum Mean Square Error and Linear Minimum Mean Square Error, Based on singular value of the Minimum Mean Square Error, rule of Maximum Likelihood, in view of the above foundation estimation method are analyzed in the simulation results.Also studied the different interpolation method based on comb pilot to estimate the influence of the performance, analyzed the simulation results.Especially on the basis of the least squares, based on the idea of threshold threshold and iteration, traverse the entire time domain do many times to deal with the noise of channel impulse response, the simulation results can be seen, greatly improve the performance of least squares estimate.The channel estimation algorithm based on DFT can in between the LS and MMSE estimation will obtain a good compromise between performance and the complexity of algorithm.The traditional method based on DFT is adopted on the cyclic prefix outside of channel impulse response do zero processing to noise.This paper mainly studied by threshold setting to remove noise within the cyclic prefix.Compared with traditional for cyclic prefix of zero estimation method, not only further reduce the computational complexity, and improve the estimation performance of the system.