| Summary: | 碩士 === 逢甲大學 === 電機工程學系 === 89 === The technology of multi-carrier modulation, such as Orthogonal Frequency Division Multiplexing (OFDM), has been adopted for high-speed data wireless mobile communication. As multimedia age is coming, the transmission of a large number image data will need higher data rate. At the same time, the problem of inter-symbol interference (ISI) becomes more and more serious and needs more care about it. In previous implementation of channel equalizer, time-domain adaptive filters are usually adopted to resolve ISI. Though the time-domain implementation is very straightforward and easy, the order required for the filter is generally high and the computation effort is heavy. Therefore, for high rate data transmission, time-domain implementation of channel equalization becomes more and more complex. In OFDM systems, guard bands are appended after data to mild the effect of ISI, but the system efficiency is lowered down. On the other hand, the frequency-domain implementation of channel equalizers has the advantages of fast converge rate and lower computation effort. It is thus considered in this research proposal for equalization in OFDM systems. Moreover, because the transmitting signal in an OFDM system is basically through IFFT and then multi-carrier modulated, the transmitted signal can be recognized as multi-components (frequency beams) one.
Hence it is intuitive to think of the use frequency-domain equalizer for channel equalization, which occurs between the carrier demodulation and FFT. This may be expected to lower the system complex and have better performance in channel equalization. Thus it is our purpose to design and configure an OFDM system using frequency-domain implementation for channel equalization.
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