Study On Frequency Offset Estimation In High-Speed Mobile Environment

Rapid modern mobile communication technology has brought tremendous changes about thedevelopment of human life and create endless wealth to society, with the rising speed of thetransport, the requirement of communication technology is increasing high, One of the importantfor high-speed mobile environment is how to estimation frequency offset fleetly and accurately,This thesis take the OFDM System for an example to have in-depth research about the frequencyoffset estimation algorithm.OFDM System received widespread attention because of its high spectral efficiency, betterresistance to multipath fading, but it is sensitive to the frequency deviation, especially in thehigh-speed mobile environment, the system will be subject to the influence of the Doppler shift. itcan destroy the orthogonality between the sub-carrier and induce the inter-carrier interference whichmay affect the performance of the system severity.This thesis first introduces some characteristics of the high-speed mobile environment, includingthe multipath fading, Doppler frequency shift, wireless channel models and parameters. thenintroduce the basic principle of OFDM System, including the basic block diagram, system structurediagram, and on this basis, summarizes the advantages and disadvantages of OFDM System. Afterthis we begin to introduce the impact about symbol timing synchronization to frequency offset,symbol timing synchronization is the premise of the frequency offset estimation algorithm. Finallywe began to discuss the carrier frequency offset estimation algorithm, it can divided into pilotsymbol-aided,data-aided and non-data-aided, about pilot symbol-aided algorithm we focuses on theMoose algorithm which belong to MLE algorithm ,traditional PSA algorithm, iterative algorithmsof PSA, After analyse the algorithm above, we proposed an improved PSA algorithm. due to thehigh complexity of hardware if implement the non-data-aided algorithm, so this thesis onlydiscussed the data-aided algorithm, We take the SCA algorithm for an example to discuss, this kindof algorithms are mostly obtain better performance only when the mobile speed is not high, if not itcan not find a balance between the frequency offset estimation accuracy and frequency offsetestimation range, so we mend the SCA algorithm to be improved.