| Summary: | 碩士 === 國立中山大學 === 通訊工程研究所 === 103 === Multi-carrier code division multiple access (MC-CDMA) systems experience serious multiple access interference (MAI) in uplink transmission because the orthogonality among codes is destroyed by the frequency-selective fading channels. A novel MC-CDMA system is proposed to avoid MAI by adopting the frequency-domain equivalents of the perfect Gaussian integer sequences as the spreading codes. However, multiple carrier-frequency offsets also induce MAI, which continues to exist in the novel MC-CDMA system. This thesis considers the effect of multiple carrier-frequency offsets (CFOs). We derive the signals-to-interference-plus-noise ratio of the novel MC-CDMA systems. In addition, a successive interference cancellation (SIC) method is proposed to mitigate MAI caused by multiple CFOs. Simulation experiments demonstrate that the improvements of the proposed SIC method for quadrature phase-shift keying after performing four iterations is 20 dB at a bit-error-rate of 10-3 . Notably, the BER performance of the proposed SIC method after performing four iterations is similar to that of the novel MC-CDMA systems without any carrier-frequency offset.
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