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標題: Study of Golay Sequences in Pre-Transformed OFDM Systems
作者: 陳後守
關鍵字: 應用研究
摘要: This project proposal investigates the Golay complementary sequences in a Pre-transformed OFDM system. The principle of orthogonal frequency division multiplexing (OFDM) is to split a high rate bit stream into several parallel low rate data substreams and use these substreams to modulate a number of orthogonal subcarriers. Recently, a novel modulation scheme, which combines the Walsh-Hadamard transform with OFDM (WHT-OFDM), is under investigation. In WHT-OFDM, the Walsh-Hadamard matrix is added before the fast Fourier transform (FFT) or equivalently the transmitted data is first spread by the discrete-time Walsh-Hadamard sequences and then modulated with the continuous-time sinusoidal signals. Thus, a WHT-OFDM system is equivalent to a combination of multi-code CDMA and OFDM.Golay sequences of OFDM can be obtained from certain cosets of the first order Reed-Muller (RM) code within the second order RM code. As with OFDM, we have derived some results regarding the binary Golay sequences in WHT-OFDM, which also composed of some certain second-order cosets of first order RM codes. Moreover, based on these results, we have shown that the number of binary Golay sequences in WHT-OFDM is much larger than those in OFDM systems. In the first year of this proposal, we would like to extend these results to nonbinary WHT-OFDM system, by classifying and enumerating the WHT-OFDM Golay sequences on QAM modulations. Since OFDM and WHT-OFDM systems are special cases of two-step orthogonal transforms which consisting of one discrete-time and one continuous-time orthogonal transforms, therefore, we will also consider the Golay sequences for other discrete-time transforms, in addition to Walsh-Hadamard transform in the second year of this proposal.
其他識別: NSC96-2221-E005-005-MY2
Appears in Collections:電機工程學系所



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