Research On Method Of Frequency Offset Estimation In OFDM System Based On Adaptation Theory

In this thesis, adaptive frequency offset estimation methods are deeply analyzed and researched. At the same time, two improved algorithms are compared with the original algorithm. The main innovation of this paper is as follows:1, Influence of frequency offset to OFDM system performance is analyzed. The influence of frequency offset on bit error rate (BER) of OFDM system, which is exposed to the additive white Gaussian noise environment, is investigated comprehensively and confirmed by computer simulations.2, Improve the algorithm's estimation accuracy. Adaptive frequency offset estimation methods of OFDM system, under the additive white Gaussian noise, are research researched deeply. Two improved algorithms based on CP, which are able to obtain higher frequency offset estimation accuracy, are proposed.3, Improve the algorithm's convergence speed. OFDM frequency offset estimation algorithm on the basis of ensuring the accuracy, in order to improve the convergence speed (ie frequency synchronous speed), the iterative calculation using variable step size factor, that is, in the initial stage of convergence, using the larger step growth factor, and in the convergence of steady-state phase, the use of small step size. Because that, in the initial stage, the estimation error is larger than steady-state phase, the step factor and estimation error are linked to design a new step size update formula, which makes the algorithm not only has fast convergence speed and tracking speed, but also has a small steady-state error.