| The goal of next generation wireless mobile communication system is to support high quality, high speed mobile multimedia services. There are lots of disadvantages in wireless environment, such as multi-paths fading, Doppler frequency shift and fast time varying of channel. OFDM technology is a kind of transmitting way to solve effectively the inter symbol interference caused by multi-paths. MIMO technology is the significant breakouts in smart antenna technology of wireless communication field, it can significantly improve system capacity and using rate of frequency. Space-time code is such an effective way to improve system capacity through combination against wireless fading. Two advantages can be achieved by combing OFDM and MIMO technologies, one is to obtain very high system capacity, other is to obtain the very strong reliability through combination.In this paper, the basic discipline of OFDM, the advantage and disadvantages of OFDM system, space-time channel model, the system model and coding method of space-time code are introduced in detail. System graphs of space-time code and MIMO-OFDM are designed. The performances of space-time code in OFDM system are processed using theory analysis method. At last, the code error rate performances in different coding method and different channel environment are analyzed and compared. |
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