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The Key Technology Research, The Application Of Ofdm In Uav Communications Link

Posted on:2008-07-18Degree:MasterType:Thesis
Country:ChinaCandidate:W CongFull Text:PDF
GTID:2192360212979029Subject:Circuits and Systems
Abstract/Summary:PDF Full Text Request
Unmanned air vehicle (UAV) is one of the focuses of the development in military technique, because it can hover a long time in the very high or low altitude and meet the requirements of modern warfare to reduce or avoid casualties. UAV needs the support of communication system for flying in safety and the implementation of the various tasks. Therefore, the communication link of UAV is the key of UAV development. Because the communication channel between UAV and its ground control station is generally frequency selective fading, using single carrier need high order equalizer to attain high speed and large capacity communication, which is difficult in hardware design. As a kind of multicarrier transmission technology, OFDM can effectively reduce the affect of ISI which is caused by multi-path delay. The application of OFDM in UAV communication link can alleviate multi-path delay to raise communication rate and mitigate frequency selective fading. In this dissertation, we comprehensively analyze the characteristic of aeronautical channel, in particular, the WSSUS model of time varying channel, and then focus the research on OFDM application in UAV communication link and frequency offset estimation algorithm. First of all, we accomplish the estimation of channel and frequency offset by using pilot tone. Then we propose the mode of inserting pilot tone. We present an adaptive Wiener filter which is used to estimate the channel parameters by combining an adaptive algorithm with the Wiener filter. Finally we study the effects of frequency offset on the orthogonality between sub-carriers, and design special pilot tone to estimate frequency offset.
Keywords/Search Tags:UAV Communication Link, OFDM, WSSUS Model, Channel Estimation, Frequency Offset Estimation
PDF Full Text Request
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