Research On Application Of DCT Interpolation Algorithm In OFDM Acoustic Channel Estimation

In order to realize the high speed, reliable underwater acoustic communication, the most important thing is to design a system of underwater acoustic communication with excellent performance. However, the accuracy of the channel estimation is one of the factors which affect the performance of underwater acoustic communication system. The DCT interpolation algorithm has been applied to the spatial wireless channel, however the acoustic channel is more greater in time delay and complexity than the spatial wireless channel, and at present the performance of the channel estimation algorithm applied to the acoustic channel is not enough ideal. Therefore, this paper focuses on the application of the DCT interpolation algorithm on the acoustic channel estimation, particularly deep researches the performance of the DCT interpolation algorithm in the acoustic channel whose multi-path time delay is decimal times sampling interval.Firstly, begin with introducing the basic principle of the OFDM acoustic communication in detail, followed by studying the channel, one part of the system. Furthermore, this paper analysis the impact of the channel to the signal, and builds a model and simulates for the channel. Secondly, studies the technology of channel estimation based on pilot. Analyses and discusses the three key problems in detail, e.g. choosing the pilot pattern and inserting position, estimation of channel response of Pilot place and restoring the complete channel response. Simulates and compares the performance of the different estimation methods and interpolation algorithm. Finally, studies the channel estimation algorithm of DCT-based interpolation, in the condition of that the time delay is decimal times sampling interval. Makes improvements on the basis of the traditional algorithm, adds the function of iterative denoising, and simulates and compares the performance of the algorithms in different channel conditions.Theory and simulation results show that DCT-based interpolation channel estimation algorithm, to some extent, solves the problem of performance degradation of other underwater acoustic channel estimation algorithms when the multi-path delay is decimal times sampling interval. The existing problems are signal dispersion, spectrum energy revealing, high frequency aliasing error and etc. In addition, the channel estimation algorithm based on DCT has better inhibition action to noise and interference of system.