| Othogonal frequency division multiplication is one of the key technologies in today's mobile communication research field. This technology is considerably robust in multi-path environments with high spectrum efficiency. Thus, it is very suitable for the high-rate data services in wireless applications and has drawn universal attention. Currently, OFDM, which has become the fundermental technology of WLAN protocol IEEE802.11a, European Digtial Audio Broadcasting (DAB),Digital Video Broadcasting (DVB), etc, is also regarded as one of the most popular schemes of the 4G mobile systems.At the beginning of this dissertation, the basic principles of OFDM are illustrated in detail. A DFT based OFDM system diagram is given after emphasizing the orthogonal characteristics.Then, two common protocols, IEEE802.11a and DVB-T, are briefly introduced respectively. The former is based on burst OFDM signal and applied in indoor WLAN environment, while the latter utilizes the continual OFDM signal mainly in the MAN circumstances.The synchronization problem is discussed in detail afterwards. The synchronization parameters are defined in order to demonstrate the effect of them. Hereafter, some effective synchronization algorithms are put forth to eliminate these effects. The algorithms include not only the data aided, but also the blind ones.Channel estimation is another focal topic of this dissertation. Firstly, a reasonable multi-path model is constructed. Secondly, some classical channel estimation algorithms, like MMSE, SVD, LS and Subspace based blind ones, are strictly deduced and simulated. Finally, a comparison between them is made in the result analysis part.Finally,"OFDM system simulation software"is briefly introduced, which contains functional overview and manipulating instructions. |
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