| Recently, data transmission rate in the communication networks for now cannot satisfy the demand of users with the explosive development of wireless communication technique, so people make a flurry of research and development activities dedicated to 4G mobile communication systems. MC-CDMA is an integrated technology of OFDM and CDMA. This technology is considered as the core technology of the future 4G wireless communications, because it kept the advantages of OFDM and CDMA, and can be used for multimedia data transmission.In this paper, based on the poly-phase orthogonal sequences presented by Naoki Suehiro, the correlation properties of poly-phase orthogonal sequences wave are studied deeply. Firstly, based on the deeply understanding of the MC-CDMA system, the author proposed a new transmitter and receiver figures of the MC-CDMA system, applied the simulink models to establish the MC-CDMA system figure.Secondly, based on the poly-phase orthogonal sequences presented by Naoki Suehiro, applied the quadriphase orthogonal sequences to the new MC-CDMA system. Through the simulation with simulink, it shows that the poly-phase orthogonal sequences can be applied to the spreading spectrum system MC-CDMA.Thirdly, the author analyzed the properties of MC-CDMA with two different methods. Fourthly, in the AWGN,Rayleigh fading channels, when the quadriphase orthogonal sequences as the spreading spectrum sequences, simulation was done by MATLAB. Fifth, the error bit rates were compared, when quadriphase orthogonal sequences and Walsh sequences were applied to the MC-CDMA system. The results show that the properties of quadriphase orthogonal sequences are better than that of Walsh, it farther shows that the quadriphase orthogonal sequences can be used in communication.Last, the author analyzed the properties of MC-DS-CDMA. the error bit rates of the MC-CDMA and MC-DS-CDMA were compared, whether it is multi user or one user ,the error bit rates of MC-CDMA is smaller than that of MC-DS-CDMA. |
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