Research On Key Technologies And Simulation Of OFDM

This thesis is focused on the research of the key technologies of the 4G mobile communication—OFDM(Orthogonal Frequency Division Modulation). However, OFDM is sensitive to channel estimation error and synchronization error and it has the weakness of the high Peak-to-Average Power Ratio (PAPR) of the transmitted signal. Against these problems, the thesis has mainly focused on the three key technologies about channel estimation, reducing PAPR and synchronization for the OFDM systems in the receiver.For respective three technologies, the thesis firstly summarize the algorithms from other papers, secondly research on the representaive algorithms of them. For example, the LS, MMSE algorithms for channel estimation, SLM, PTS algorithms for reducing high PAPR, some Timing (included T.Schmidl and D.Coxt algorithm, H.Minn algorithm and Xiaozhun Cui algorithm) and Frequency synchronization algorithms and maximum-likelihood (ML) estimation of time and frequency offset in OFDM systems, then compared the differences of these algorithms by Matlab simulation.Finally, the thesis presents a Simulation Platform of the whole OFDM communication system which includes the transmitter, channel and receiver. The channel estimation technology is introduced into the Simulation Platform. From the simulation, the conclusion which the stable Constellation can be gained after the channel estimation is presented. Also we compare the BER performance in different input signal power and different SNR.Above all, the thesis has proposed ten algorithms about the three key technologies and presented a scheme the Simulation Model. OFDM, with the advantage of high spectrum efficiency, can strongly combat multi-path and dispersive channel interference, so it will apply to the next generation communication systems.