| The 4G Mobile Communication systems will provide a bit rate of 10M-20Mbps or even lOOMbps as a best. It can support a few multimedia services, such as data, graph and video service. While in mobile communications, bandwidth is a very rare resource. Orthogonal Frequency Division Multiplexing (OFDM) has been one of the key techniques in fourth generation mobile communication systems due to its high data rate transmission capability with high bandwidth efficiency, flexible modulation modes and its robustness to multi-path delay.It separates the communication channel into many orthogonal subchannels, which are orthogonal and overlapping each other, thus, the inter-subchannel interferences can be decreased and the utilization of frequency spectrum be increased. With people's increasing demand on broad band, individualizing and moving. OFDM technology will be used widely in the field of wireless communication.In this thesis the development of mobile communication, wireless communication channel and the principle of OFDM system are first introduced. In the following, the theory of OFDM technology is focused on. The system model and the theory of guard period are analyzed. The current situation of OFDM and its advantages and disadvantages are also summarized. The ability of OFDM to resist the multipath fading, AWGN noise, the error of synchronization and also its ability to reduce the code error rate that is caused by signal clipping in the condition of high PAPR are simulated. Based on the above work, the different performances of some sub-carrier modulation schemes, such as PSK, QPSK and 16PSK, are compared. OFDM system is... |
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