| The need for wireless data and multimedia services promotes the development and applications of many high-speed wireless communication techniques. Multiple-Input Multiple-Output (MIMO) technique, offers an effective way to combat and even exploit fading. Another technique, Orthogonal Frequency Division Multiplexing (OFDM), proposed in 1960s, now has gained much attention with its ability to reduce system complexity. The combination of MIMO and OFDM has been regarded as a potential candidate for Forth Generation (B3G/4G) mobile communication, and also has been adopted into the WLAN standard. But there are still some key problems to be solved. Synchronization is very important for MIMO-OFDM system because it is very sensitive to time and frequency offset. It is the research target in this paper.For the B3G project of UESTC, in chapter 3 we proposed a scheme of synchronization for MIMO-OFDM system. In time synchronization, we adopted some methods to reduce the probability of false and omit. Based on the needs of the hardware implementation, we reduced the complexity of the algorithm without reducing the synchronization performance. In frequency synchronization, we mainly discussed two algorithms of fine frequency synchronizations, and compared them with each other. We adopted the algorithm based on cyclic prefix as the fine frequency synchronization for the system.But the application of the scheme in chapter 3 is not suitable for the distributed MIMO systems. So in chapter 4 we proposed a novel synchronization algorithm for MIMO-OFDM system. It is applicable to the conditions where all the transmit antennas have different delays, is more generalized in broad sense. Therefore it can be used in the distributed MIMO systems.In chapter 5, we proposed a novel synchronization algorithm in the WLAN systems. In time synchronization, we got better performance by the controlling of the polarity of training sequences using PN code. In frequency synchronization, we used the... |
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