Channel Estimation Based On DFT And LS In OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) technology, due to the high frequency spectrum efficiency and strong anti-jamming ability, has received extensive attention, and has gradually become one of the core technology of the next generation of wireless communication system.Channel estimation is one of the key techniques in OFDM systems, and of all the channel estimation algorithms in OFDM systems, this paper mainly studies channel estimation(CE) algorithm based on the Least Square (LS) and Discrete Fourier Transform (DFT) interpolation. CE algorithm based on DFT interpolation is a trade-off between complexity and performance among all sorts of interpolation algorithms. This paper firstly makes a detailed analysis of the traditional CE algorithm based on DFT both in time and transform domain, and then in the light of the defects of the LS criterion, puts forward the threshold value method and transform domain filtering method to eliminate noise effects. And because of the remaining noise being spread to other sub-carriers via interpolation, this paper combines CE algorithm based on decision feedback with that based on DFT, which is a secondary filtering algorithm and further filters the noise.This paper uses COST 207TU six paths channel model and M.1225 indoor office channel B model as channel models in the MATLAB simulation OFDM system. Several kinds of CE algorithm based on DFT are tested respectively in simulation OFDM system. Simulation results show that the threshold method and transform filtering method, can greatly improve the algorithm of performance as opposed to a no-filtering one, 5dB performance improvement in low high signal-to-noise ratio (SNR) system especially. The performance is further improved, 5dB performance improvement in high SNR system especially when using the secondary filtering algorithm...