Research Of OFDM Channel Estimation Based On Pilot

The Technology of Orthogonal Frequency Division Multiplexing (OFDM) has been regarded as the core technology of 4 Generation(4G) wireless communications system。Orthogonal multiple sub-carriers is used in parallel transmission scheme, which has the merits such as good capability of countering multi-path interference, high utilization of frequency spectrums. It is also adaptive to high-rate data transmission. Channel estimation is a very important part for OFDM systems. In this thesis, we study channel estimation methods and interpolation methods in OFDM systems, then apply them to link-level simulation. Through the simulations and comparisons of different channel estimation arithmetic and different interpolation methods, the conlusion could be used for reference in other communication systems.The channel estimation based on the pilot is the main part which the paper reseaches. Firstly, it introduces the development of mobile communications, the principles of OFDM and wireless channel, describes several key technologies of OFDM system, advances the parameters of the whole OFDM system and wireless channel; Secondly, it introduces the arithmetic of channel estimations, discusses the choices of pilot patterns and pilot arrangements, and described Least Square (LS) algorithm, Minimum Mean Squared Error (MMSE) algorithm, Singular Value Decomposition (SVD) algorithm. Analyses different interpolation methods including constant interpolation, linear interpolation, Gaussian interpolation, sinc interpolation, DFT interpolation, simulates and compares the performance. Studies the interpolation method based on Discrete Cosine Transform (DCT), simulates and compares the performance of DCT/IDCT and IDCT/DCT interpolation methods. Studies channel estimation based on the time domain, simulates and compares the channel estimation based on PN sequence and channel estimation based on the LS algorithm; Finally advances two improved methods, one is Improved Pilots Filtering (IPF), the other is Improved Data Filtering (IDF) channel estimation algorithm. Analyses the influences to improved methods in two aspects, one is cut-off frequency, the other is FIR filter step counts.