| Summary: | 碩士 === 景文科技大學 === 電子工程系電腦與通訊碩士班 === 103 === Orthogonal frequency division multiplexing (Orthogonal Frequency-Division Multiplexing, OFDM) is a multi-carrier (Multicarrier, MC) transmitted by the system, and multi-carrier transmission technique is a kind of good effect. Orthogonal frequency division multiplexing and code division multiple access (Code-Division Multiple Access, CDMA) combination is known as OFDM-CDMA, recently attracted a lot of interest in wireless communications research personnel. This paper evaluated OFDM-CDMA receiver in two forms in the effectiveness of adaptive downlink multipath channel: 1 multi-carrier code division multiple access (Multicarrier Code-Division Multiple Access, MC-CDMA) 2. Multi- carrier direct sequence code division multiple access (Multicarrier Direct-Sequence Code Division Multiple Access, MC-DS-CDMA). We MC-CDMA and MC-DS-CDMA under different circumstances comparison system performance. One disadvantage of multicarrier systems is the carrier frequency offset (Carrier Frequency Offset, CFO) reduced efficiency of the system, therefore, this thesis, MC-CDMA and MC-DS-CDMA systems are two of the carrier frequency offset value is 0.5,0.05,0.01, under three carrier frequency offset compared. Simulation results showed that a small amount of a carrier frequency offset (0.05 and 0.01) the impact on the system performance gap is small, and the carrier frequency offset of 0.5 system failure. For MC-CDMA and MC-DS-CDMA when comparing the two systems can be found, MC-CDMA system performance better than the MC-DS-CDMA.
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