Simulation And Design Of Channel Estimation Based On DCT Interpolation For OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) is a kind of multi-carriermodulation technology. To be the one of the cores of the fourth generation mobilecommunication technology, it has attracted a lot of attention because of its good spectralefficiency and resistance to fading channel capacity.Channel estimation is one of the key technologies for the OFDM system. We all knowthat coherent demodulation need to use the channel information, so we must estimation andtrack the characteristics in real time to obtain the channel state information timely at thereceiving end. In OFDM system, the channel estimation affects the system performanceimmediately and has a significant importance.At present, OFDM channel estimation techniques can be divided into three categories:the pilot-based channel estimation techniques, blind channel estimation techniques andsemi-blind channel estimation techniques. In this thesis, only the pilot-based channelestimation method is investigated. Firstly, the study gives a detailed description on the basicprinciples of the OFDM system, introduced the basic concepts and principles, systemcomponents and key technologies of the OFDM system. Then this paper presents the channelestimation technology in OFDM system. The presentation of the channel estimationalgorithm by the traditional methods, though its analysis and comparison, for its lacks suggestfor improvements. This paper is mainly studied channel estimation algorithm based on theDiscrete Fourier Transform (DFT) and Discrete Cosine Transform (DCT) interpolation.Compared with DFT transform, DCT transform avoids the complex calculation, thecomplexity is decreased relatively and the energy is more concentrated. Therefore, DCTinterpolation channel estimation algorithm can well suppress spectrum leakage. And becauseof the remaining noise being spread to other sub-carriers via interpolation, a novel channelestimation algorithm based on DCT with direct-decision is proposed, which to filter noisewith the second time. The simulation results show that this proposed algorithm can partlyreach the purpose of further denoising, and improve the performance of channel estimation. Finally, the thesis has carried on the modeling and simulation of the OFDM system onthe Simulation Platform of MATLAB software including the transmitter, channel andreceiver. This article focuses on the affect of the LS channel estimation module to theperformance of OFDM system. From the transceiver power spectral density, transceiversignal constellation diagram and system parameters to study the performance of the OFDMsystem. On this basis this article builds a model diagram based on DCT interpolation channelestimation algorithm. The model diagram simulation improves the performance of the OFDMsystem.